docs: pin down sphinx to avoid crash with Sphinx 3.0.0

The vpp-make-test-docs-verify jobs started to fail. The last successful run of it shows:

reating file /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api/vpp_vxlan_gbp_tunnel.rst.
Creating file /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api/vpp_vxlan_tunnel.rst.
Creating file /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api/vrf.rst.
Creating file /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api/modules.rst.
sphinx-build -b html -d /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/.sphinx-cache  /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api -c /w/workspace/vpp-make-test-docs-verify-master/test/doc /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/html
Running Sphinx v2.4.4
making output directory... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 161 source files that are out of date
updating environment: [new config] 161 added, 0 changed, 0 removed
reading sources... [  0%] bfd
reading sources... [  1%] debug
reading sources... [  1%] debug_internal
reading sources... [  2%] discover_tests

The failing jobs show:

Creating file /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api/vpp_vxlan_tunnel.rst.
Creating file /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api/vrf.rst.
Creating file /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api/modules.rst.
sphinx-build -b html -d /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/.sphinx-cache  /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/api -c /w/workspace/vpp-make-test-docs-verify-master/test/doc /w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc/html
Running Sphinx v3.0.0
making output directory... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 161 source files that are out of date
updating environment: [new config] 161 added, 0 changed, 0 removed
reading sources... [  0%] bfd

Exception occurred:
  File "/usr/lib/python3.6/inspect.py", line 516, in unwrap
    raise ValueError('wrapper loop when unwrapping {!r}'.format(f))
ValueError: wrapper loop when unwrapping scapy.fields.BitEnumField
The full traceback has been saved in /tmp/sphinx-err-n84dadfq.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
Makefile:39: recipe for target 'html' failed
make[2]: *** [html] Error 2
make[2]: Leaving directory '/w/workspace/vpp-make-test-docs-verify-master/test/doc'
Makefile:274: recipe for target '/w/workspace/vpp-make-test-docs-verify-master/build-root/build-test/doc' failed

Type: fix

Change-Id: Id98c0f94104e455ea819aacec62f605e53db13ce
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>

2 files changed, 121 insertions, 1 deletions

diff --git a/test/requirements-3.txt b/test/requirements-3.txt
index f5dbc22c4c9..77a3d35d724 100644
--- a/test/requirements-3.txt
+++ b/test/requirements-3.txt
@@ -4,10 +4,22 @@
 #
 #    make test-refresh-deps (or update requirements.txt)
 #
+alabaster==0.7.12 \
+    --hash=sha256:446438bdcca0e05bd45ea2de1668c1d9b032e1a9154c2c259092d77031ddd359 \
+    --hash=sha256:a661d72d58e6ea8a57f7a86e37d86716863ee5e92788398526d58b26a4e4dc02 \
+    # via sphinx
 asn1crypto==0.24.0 \
     --hash=sha256:2f1adbb7546ed199e3c90ef23ec95c5cf3585bac7d11fb7eb562a3fe89c64e87 \
     --hash=sha256:9d5c20441baf0cb60a4ac34cc447c6c189024b6b4c6cd7877034f4965c464e49 \
     # via cryptography
+babel==2.8.0 \
+    --hash=sha256:1aac2ae2d0d8ea368fa90906567f5c08463d98ade155c0c4bfedd6a0f7160e38 \
+    --hash=sha256:d670ea0b10f8b723672d3a6abeb87b565b244da220d76b4dba1b66269ec152d4 \
+    # via sphinx
+certifi==2020.4.5.1 \
+    --hash=sha256:1d987a998c75633c40847cc966fcf5904906c920a7f17ef374f5aa4282abd304 \
+    --hash=sha256:51fcb31174be6e6664c5f69e3e1691a2d72a1a12e90f872cbdb1567eb47b6519 \
+    # via requests
 cffi==1.12.3 \
     --hash=sha256:041c81822e9f84b1d9c401182e174996f0bae9991f33725d059b771744290774 \
     --hash=sha256:046ef9a22f5d3eed06334d01b1e836977eeef500d9b78e9ef693f9380ad0b83d \
@@ -37,6 +49,10 @@ cffi==1.12.3 \
     --hash=sha256:e070535507bd6aa07124258171be2ee8dfc19119c28ca94c9dfb7efd23564512 \
     --hash=sha256:e1ff2748c84d97b065cc95429814cdba39bcbd77c9c85c89344b317dc0d9cbff \
     --hash=sha256:ed851c75d1e0e043cbf5ca9a8e1b13c4c90f3fbd863dacb01c0808e2b5204201
+chardet==3.0.4 \
+    --hash=sha256:84ab92ed1c4d4f16916e05906b6b75a6c0fb5db821cc65e70cbd64a3e2a5eaae \
+    --hash=sha256:fc323ffcaeaed0e0a02bf4d117757b98aed530d9ed4531e3e15460124c106691 \
+    # via requests
 click==7.0 \
     --hash=sha256:2335065e6395b9e67ca716de5f7526736bfa6ceead690adf616d925bdc622b13 \
     --hash=sha256:5b94b49521f6456670fdb30cd82a4eca9412788a93fa6dd6df72c94d5a8ff2d7 \
@@ -61,6 +77,10 @@ cryptography==2.7 \
 deprecation==2.0.6 \
     --hash=sha256:68071e5ae7cd7e9da6c7dffd750922be4825c7c3a6780d29314076009cc39c35 \
     --hash=sha256:fecd0f05024126466ba7e5309b905f09fce7d25d67e4648f7ec5488f9e764310
+docutils==0.16 \
+    --hash=sha256:0c5b78adfbf7762415433f5515cd5c9e762339e23369dbe8000d84a4bf4ab3af \
+    --hash=sha256:c2de3a60e9e7d07be26b7f2b00ca0309c207e06c100f9cc2a94931fc75a478fc \
+    # via sphinx
 entrypoints==0.3 \
     --hash=sha256:589f874b313739ad35be6e0cd7efde2a4e9b6fea91edcc34e58ecbb8dbe56d19 \
     --hash=sha256:c70dd71abe5a8c85e55e12c19bd91ccfeec11a6e99044204511f9ed547d48451 \
@@ -72,9 +92,56 @@ graphviz==0.11 \
     --hash=sha256:6f261efbe92b938808ebb64048253b99f379f6300c6c776d440984e71678f642 \
     --hash=sha256:fc6f825a2a1be9841c1c7493777c0c742514c7daf979691f0e143d7dc0cc1fa9 \
     # via objgraph
+idna==2.9 \
+    --hash=sha256:7588d1c14ae4c77d74036e8c22ff447b26d0fde8f007354fd48a7814db15b7cb \
+    --hash=sha256:a068a21ceac8a4d63dbfd964670474107f541babbd2250d61922f029858365fa \
+    # via requests
+imagesize==1.2.0 \
+    --hash=sha256:6965f19a6a2039c7d48bca7dba2473069ff854c36ae6f19d2cde309d998228a1 \
+    --hash=sha256:b1f6b5a4eab1f73479a50fb79fcf729514a900c341d8503d62a62dbc4127a2b1 \
+    # via sphinx
+jinja2==2.11.1 \
+    --hash=sha256:93187ffbc7808079673ef52771baa950426fd664d3aad1d0fa3e95644360e250 \
+    --hash=sha256:b0eaf100007721b5c16c1fc1eecb87409464edc10469ddc9a22a27a99123be49 \
+    # via sphinx
 lark-parser==0.6.7 \
     --hash=sha256:062800f3823a6c733ec1d181a2089a22d1f62dbe65f90a3f6b1e6de1934b05ef \
     # via syslog-rfc5424-parser
+markupsafe==1.1.1 \
+    --hash=sha256:00bc623926325b26bb9605ae9eae8a215691f33cae5df11ca5424f06f2d1f473 \
+    --hash=sha256:09027a7803a62ca78792ad89403b1b7a73a01c8cb65909cd876f7fcebd79b161 \
+    --hash=sha256:09c4b7f37d6c648cb13f9230d847adf22f8171b1ccc4d5682398e77f40309235 \
+    --hash=sha256:1027c282dad077d0bae18be6794e6b6b8c91d58ed8a8d89a89d59693b9131db5 \
+    --hash=sha256:13d3144e1e340870b25e7b10b98d779608c02016d5184cfb9927a9f10c689f42 \
+    --hash=sha256:24982cc2533820871eba85ba648cd53d8623687ff11cbb805be4ff7b4c971aff \
+    --hash=sha256:29872e92839765e546828bb7754a68c418d927cd064fd4708fab9fe9c8bb116b \
+    --hash=sha256:43a55c2930bbc139570ac2452adf3d70cdbb3cfe5912c71cdce1c2c6bbd9c5d1 \
+    --hash=sha256:46c99d2de99945ec5cb54f23c8cd5689f6d7177305ebff350a58ce5f8de1669e \
+    --hash=sha256:500d4957e52ddc3351cabf489e79c91c17f6e0899158447047588650b5e69183 \
+    --hash=sha256:535f6fc4d397c1563d08b88e485c3496cf5784e927af890fb3c3aac7f933ec66 \
+    --hash=sha256:596510de112c685489095da617b5bcbbac7dd6384aeebeda4df6025d0256a81b \
+    --hash=sha256:62fe6c95e3ec8a7fad637b7f3d372c15ec1caa01ab47926cfdf7a75b40e0eac1 \
+    --hash=sha256:6788b695d50a51edb699cb55e35487e430fa21f1ed838122d722e0ff0ac5ba15 \
+    --hash=sha256:6dd73240d2af64df90aa7c4e7481e23825ea70af4b4922f8ede5b9e35f78a3b1 \
+    --hash=sha256:717ba8fe3ae9cc0006d7c451f0bb265ee07739daf76355d06366154ee68d221e \
+    --hash=sha256:79855e1c5b8da654cf486b830bd42c06e8780cea587384cf6545b7d9ac013a0b \
+    --hash=sha256:7c1699dfe0cf8ff607dbdcc1e9b9af1755371f92a68f706051cc8c37d447c905 \
+    --hash=sha256:88e5fcfb52ee7b911e8bb6d6aa2fd21fbecc674eadd44118a9cc3863f938e735 \
+    --hash=sha256:8defac2f2ccd6805ebf65f5eeb132adcf2ab57aa11fdf4c0dd5169a004710e7d \
+    --hash=sha256:98c7086708b163d425c67c7a91bad6e466bb99d797aa64f965e9d25c12111a5e \
+    --hash=sha256:9add70b36c5666a2ed02b43b335fe19002ee5235efd4b8a89bfcf9005bebac0d \
+    --hash=sha256:9bf40443012702a1d2070043cb6291650a0841ece432556f784f004937f0f32c \
+    --hash=sha256:ade5e387d2ad0d7ebf59146cc00c8044acbd863725f887353a10df825fc8ae21 \
+    --hash=sha256:b00c1de48212e4cc9603895652c5c410df699856a2853135b3967591e4beebc2 \
+    --hash=sha256:b1282f8c00509d99fef04d8ba936b156d419be841854fe901d8ae224c59f0be5 \
+    --hash=sha256:b2051432115498d3562c084a49bba65d97cf251f5a331c64a12ee7e04dacc51b \
+    --hash=sha256:ba59edeaa2fc6114428f1637ffff42da1e311e29382d81b339c1817d37ec93c6 \
+    --hash=sha256:c8716a48d94b06bb3b2524c2b77e055fb313aeb4ea620c8dd03a105574ba704f \
+    --hash=sha256:cd5df75523866410809ca100dc9681e301e3c27567cf498077e8551b6d20e42f \
+    --hash=sha256:cdb132fc825c38e1aeec2c8aa9338310d29d337bebbd7baa06889d09a60a1fa2 \
+    --hash=sha256:e249096428b3ae81b08327a63a485ad0878de3fb939049038579ac0ef61e17e7 \
+    --hash=sha256:e8313f01ba26fbbe36c7be1966a7b7424942f670f38e666995b88d012765b9be \
+    # via jinja2
 mccabe==0.6.1 \
     --hash=sha256:ab8a6258860da4b6677da4bd2fe5dc2c659cff31b3ee4f7f5d64e79735b80d42 \
     --hash=sha256:dd8d182285a0fe56bace7f45b5e7d1a6ebcbf524e8f3bd87eb0f125271b8831f \
@@ -85,7 +152,7 @@ objgraph==3.4.1 \
 packaging==19.0 \
     --hash=sha256:0c98a5d0be38ed775798ece1b9727178c4469d9c3b4ada66e8e6b7849f8732af \
     --hash=sha256:9e1cbf8c12b1f1ce0bb5344b8d7ecf66a6f8a6e91bcb0c84593ed6d3ab5c4ab3 \
-    # via deprecation
+    # via deprecation, sphinx
 parameterized==0.7.0 \
     --hash=sha256:020343a281efcfe9b71b9028a91817f981202c14d72104b5a2fbe401dee25a18 \
     --hash=sha256:d8c8837fb677ed2d5a93b9e2308ce0da3aeb58cf513120d501e0b7af14da78d5
@@ -119,20 +186,71 @@ pyflakes==2.1.1 \
     --hash=sha256:17dbeb2e3f4d772725c777fabc446d5634d1038f234e77343108ce445ea69ce0 \
     --hash=sha256:d976835886f8c5b31d47970ed689944a0262b5f3afa00a5a7b4dc81e5449f8a2 \
     # via flake8
+pygments==2.6.1 \
+    --hash=sha256:647344a061c249a3b74e230c739f434d7ea4d8b1d5f3721bc0f3558049b38f44 \
+    --hash=sha256:ff7a40b4860b727ab48fad6360eb351cc1b33cbf9b15a0f689ca5353e9463324 \
+    # via sphinx
 pympler==0.7 \
     --hash=sha256:7a11e739125a9ce8bf868ded67238a40e8a7bf979bc03005eb8126182e5e274e
 pyparsing==2.4.0 \
     --hash=sha256:1873c03321fc118f4e9746baf201ff990ceb915f433f23b395f5580d1840cb2a \
     --hash=sha256:9b6323ef4ab914af344ba97510e966d64ba91055d6b9afa6b30799340e89cc03 \
     # via packaging
+pytz==2019.3 \
+    --hash=sha256:1c557d7d0e871de1f5ccd5833f60fb2550652da6be2693c1e02300743d21500d \
+    --hash=sha256:b02c06db6cf09c12dd25137e563b31700d3b80fcc4ad23abb7a315f2789819be \
+    # via babel
+requests==2.23.0 \
+    --hash=sha256:43999036bfa82904b6af1d99e4882b560e5e2c68e5c4b0aa03b655f3d7d73fee \
+    --hash=sha256:b3f43d496c6daba4493e7c431722aeb7dbc6288f52a6e04e7b6023b0247817e6 \
+    # via sphinx
 scapy==2.4.3 ; python_version >= "2.7" or python_version >= "3.4" \
     --hash=sha256:e2f8d11f6a941c14a789ae8b236b27bd634681f1b29b5e893861e284d234f6b0
 six==1.12.0 \
     --hash=sha256:3350809f0555b11f552448330d0b52d5f24c91a322ea4a15ef22629740f3761c \
     --hash=sha256:d16a0141ec1a18405cd4ce8b4613101da75da0e9a7aec5bdd4fa804d0e0eba73
+snowballstemmer==2.0.0 \
+    --hash=sha256:209f257d7533fdb3cb73bdbd24f436239ca3b2fa67d56f6ff88e86be08cc5ef0 \
+    --hash=sha256:df3bac3df4c2c01363f3dd2cfa78cce2840a79b9f1c2d2de9ce8d31683992f52 \
+    # via sphinx
+sphinx==2.4.4 \
+    --hash=sha256:b4c750d546ab6d7e05bdff6ac24db8ae3e8b8253a3569b754e445110a0a12b66 \
+    --hash=sha256:fc312670b56cb54920d6cc2ced455a22a547910de10b3142276495ced49231cb
+sphinxcontrib-applehelp==1.0.2 \
+    --hash=sha256:806111e5e962be97c29ec4c1e7fe277bfd19e9652fb1a4392105b43e01af885a \
+    --hash=sha256:a072735ec80e7675e3f432fcae8610ecf509c5f1869d17e2eecff44389cdbc58 \
+    # via sphinx
+sphinxcontrib-devhelp==1.0.2 \
+    --hash=sha256:8165223f9a335cc1af7ffe1ed31d2871f325254c0423bc0c4c7cd1c1e4734a2e \
+    --hash=sha256:ff7f1afa7b9642e7060379360a67e9c41e8f3121f2ce9164266f61b9f4b338e4 \
+    # via sphinx
+sphinxcontrib-htmlhelp==1.0.3 \
+    --hash=sha256:3c0bc24a2c41e340ac37c85ced6dafc879ab485c095b1d65d2461ac2f7cca86f \
+    --hash=sha256:e8f5bb7e31b2dbb25b9cc435c8ab7a79787ebf7f906155729338f3156d93659b \
+    # via sphinx
+sphinxcontrib-jsmath==1.0.1 \
+    --hash=sha256:2ec2eaebfb78f3f2078e73666b1415417a116cc848b72e5172e596c871103178 \
+    --hash=sha256:a9925e4a4587247ed2191a22df5f6970656cb8ca2bd6284309578f2153e0c4b8 \
+    # via sphinx
+sphinxcontrib-qthelp==1.0.3 \
+    --hash=sha256:4c33767ee058b70dba89a6fc5c1892c0d57a54be67ddd3e7875a18d14cba5a72 \
+    --hash=sha256:bd9fc24bcb748a8d51fd4ecaade681350aa63009a347a8c14e637895444dfab6 \
+    # via sphinx
+sphinxcontrib-serializinghtml==1.1.4 \
+    --hash=sha256:eaa0eccc86e982a9b939b2b82d12cc5d013385ba5eadcc7e4fed23f4405f77bc \
+    --hash=sha256:f242a81d423f59617a8e5cf16f5d4d74e28ee9a66f9e5b637a18082991db5a9a \
+    # via sphinx
 subprocess32==3.5.4 \
     --hash=sha256:88e37c1aac5388df41cc8a8456bb49ebffd321a3ad4d70358e3518176de3a56b \
     --hash=sha256:eb2937c80497978d181efa1b839ec2d9622cf9600a039a79d0e108d1f9aec79d
 syslog-rfc5424-parser==0.3.1 \
     --hash=sha256:994dbb7b138ff175dd2e2a09ae487af4875cd608de9dcec25622c9b96fc0aa78 \
     --hash=sha256:ff11d711d88d98538e1a0f1bd1a89449d3e88bc5abed66e3924b1a500869cb53
+urllib3==1.25.8 \
+    --hash=sha256:2f3db8b19923a873b3e5256dc9c2dedfa883e33d87c690d9c7913e1f40673cdc \
+    --hash=sha256:87716c2d2a7121198ebcb7ce7cccf6ce5e9ba539041cfbaeecfb641dc0bf6acc \
+    # via requests
+
+# WARNING: The following packages were not pinned, but pip requires them to be
+# pinned when the requirements file includes hashes. Consider using the --allow-unsafe flag.
+# setuptools==46.1.3        # via sphinx
diff --git a/test/requirements.txt b/test/requirements.txt
index 103bc190005..40d570599b0 100644
--- a/test/requirements.txt
+++ b/test/requirements.txt
@@ -17,3 +17,5 @@ subprocess32                            # PSF
 syslog_rfc5424_parser>=0.3.1            # ISC
 objgraph                                # MIT
 pympler                                 # Apache-2.0
+# sphinx 3.0.0 crashes with a traceback
+sphinx<3.0.0