DOC: Handle exceptions when computing contributors.

[TomAugspurger]

We're failing on master right now https://travis-ci.org/pandas-dev/pandas/jobs/455255389#L4369

Exception occurred: File "/home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/git/cmd.py", line 825, in execute raise GitCommandError(command, status, stderr_value, stdout_value) git.exc.GitCommandError: Cmd('git') failed due to: exit code(128) cmdline: git shortlog -s v0.9.0..v0.10.0 stderr: 'fatal: ambiguous argument 'v0.9.0..v0.10.0': unknown revision or path not in the working tree. Use '--' to separate paths from revisions, like this: 'git <command> [<revision>...] -- [<file>...]'' The full traceback has been saved in /tmp/sphinx-err-hzfqasu4.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! 

I'm not sure why that is. Perhaps something with how the repo is cloned.

Anyway, this will work around the error.

/Users/taugspurger/sandbox/pandas/doc/source/whatsnew/v0.10.0.rst:450: WARNING: Cannot find contributors for range 'v0.9.0..v0.1.0' looking for now-outdated files... none found 

[pep8speaks]

Hello @TomAugspurger! Thanks for submitting the PR.

• There are no PEP8 issues in the file doc/sphinxext/contributors.py !

[codecov]

Codecov Report

Merging #23714 into master will not change coverage.
The diff coverage is n/a.

@@ Coverage Diff @@ ## master #23714 +/- ## ======================================= Coverage 92.24% 92.24% ======================================= Files 161 161 Lines 51336 51336 ======================================= Hits 47357 47357 Misses 3979 3979

Flag	Coverage Δ
#multiple	90.64% <ø> (ø)	⬆️
#single	42.34% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6920363...d09998e. Read the comment docs.

[TomAugspurger]

https://travis-ci.org/pandas-dev/pandas/jobs/455318447#L2203

Ignoring the Azure failed build.

Unfortunately, not even the 0.23.4..HEAD range is being picked up, but that's OK I think.

�[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.10.0.rst:450: WARNING: Cannot find contributors for range 'v0.9.0..v0.10.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.10.1.rst:232: WARNING: Cannot find contributors for range 'v0.10.0..v0.10.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.11.0.rst:354: WARNING: Cannot find contributors for range 'v0.10.1..v0.11.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.12.0.rst:528: WARNING: Cannot find contributors for range 'v0.11.0..v0.12.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.13.0.rst:1297: WARNING: Cannot find contributors for range 'v0.12.0..v0.13.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.13.0.rst:996: WARNING: duplicate label release.bug_fixes-0.13.0, other instance in /home/travis/build/pandas-dev/pandas/doc/source/release.rst�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.13.1.rst:391: WARNING: Cannot find contributors for range 'v0.13.0..v0.13.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.13.1.rst:312: WARNING: duplicate label release.bug_fixes-0.13.1, other instance in /home/travis/build/pandas-dev/pandas/doc/source/release.rst�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.14.0.rst:1071: WARNING: Cannot find contributors for range 'v0.13.1..v0.14.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.14.1.rst:293: WARNING: Cannot find contributors for range 'v0.14.0..v0.14.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.15.0.rst:1240: WARNING: Cannot find contributors for range 'v0.14.1..v0.15.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.15.1.rst:328: WARNING: Cannot find contributors for range 'v0.15.0..v0.15.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.15.2.rst:262: WARNING: Cannot find contributors for range 'v0.15.1..v0.15.2'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.16.0.rst:699: WARNING: Cannot find contributors for range 'v0.15.2..v0.16.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.16.1.rst:489: WARNING: Cannot find contributors for range 'v0.16.0..v0.16.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.16.2.rst:189: WARNING: Cannot find contributors for range 'v0.16.1..v0.16.2'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.17.0.rst:1191: WARNING: Cannot find contributors for range 'v0.16.2..v0.17.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.17.1.rst:226: WARNING: Cannot find contributors for range 'v0.17.0..v0.17.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.18.0.rst:1314: WARNING: Cannot find contributors for range 'v0.17.1..v0.18.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.18.1.rst:716: WARNING: Cannot find contributors for range 'v0.18.0..v0.18.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.19.0.rst:1588: WARNING: Cannot find contributors for range 'v0.18.1..v0.19.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.19.1.rst:83: WARNING: Cannot find contributors for range 'v0.19.0..v0.19.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.19.2.rst:104: WARNING: Cannot find contributors for range 'v0.19.1..v0.19.2'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.20.0.rst:1755: WARNING: Cannot find contributors for range 'v0.19.2..v0.20.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.20.2.rst:149: WARNING: Cannot find contributors for range 'v0.20.0..v0.20.2'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.20.3.rst:82: WARNING: Cannot find contributors for range 'v0.20.2..v0.20.3'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.21.0.rst:1200: WARNING: Cannot find contributors for range 'v0.20.3..v0.21.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.21.1.rst:193: WARNING: Cannot find contributors for range 'v0.21.0..v0.21.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.22.0.rst:265: WARNING: Cannot find contributors for range 'v0.21.1..v0.22.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.23.0.rst:1435: WARNING: Cannot find contributors for range 'v0.22.0..v0.23.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.23.1.rst:161: WARNING: Cannot find contributors for range 'v0.23.0..v0.23.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.23.2.rst:134: WARNING: Cannot find contributors for range 'v0.23.1..v0.23.2'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.23.3.rst:28: WARNING: Cannot find contributors for range 'v0.23.2..v0.23.3'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.23.4.rst:58: WARNING: Cannot find contributors for range 'v0.23.3..v0.23.4'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.24.0.rst:1426: WARNING: Cannot find contributors for range 'v0.23.4..HEAD'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.4.x.rst:81: WARNING: Cannot find contributors for range 'v0.4.1..v0.4.3'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.5.0.rst:65: WARNING: Cannot find contributors for range 'v0.4.0..v0.5.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.6.0.rst:78: WARNING: Cannot find contributors for range 'v0.5.0..v0.6.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.6.1.rst:58: WARNING: Cannot find contributors for range 'v0.6.0..v0.6.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.7.0.rst:322: WARNING: Cannot find contributors for range 'v0.6.1..v0.7.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.7.1.rst:52: WARNING: Cannot find contributors for range 'v0.7.0..v0.7.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.7.2.rst:49: WARNING: Cannot find contributors for range 'v0.7.1..v0.7.2'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.7.3.rst:118: WARNING: Cannot find contributors for range 'v0.7.2..v0.7.3'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.8.0.rst:293: WARNING: Cannot find contributors for range 'v0.7.3..v0.8.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.8.1.rst:58: WARNING: Cannot find contributors for range 'v0.8.0..v0.8.1'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.9.0.rst:114: WARNING: Cannot find contributors for range 'v0.8.1..v0.9.0'�[39;49;00m �[31;01m/home/travis/build/pandas-dev/pandas/doc/source/whatsnew/v0.9.1.rst:177: WARNING: Cannot find contributors for range 'v0.9.0..v0.9.1'�[39;49;00m