latex: add defaults for enumerated list prefix/suffix

[minrk]

Subject: enumerated lists can fail to build latex if they lack the optional prefix/suffix attributes, (e.g. if they come from recommonmark parser).

Feature or Bugfix

• Bugfix

Purpose

Adds handling for when prefix/suffix are undefined. If I understand correctly, it should not be assumed that these are always defined, since they are not part of the docutils enumerated_list object. Fixes error in make latex:

Exception occurred:
  File "/home/docs/checkouts/readthedocs.org/user_builds/minrk-jupyterhub/conda/latest/lib/python3.6/site-packages/docutils/nodes.py", line 567, in __getitem__
    return self.attributes[key]
KeyError: 'prefix'

when building with enumerated lists coming from recommonmark, e.g. with index.md:

# test

1. an
2. enumerated
3. list

and conf.py:

from recommonmark.parser import CommonMarkParser
source_parsers = {'.md': CommonMarkParser}
source_suffix = ['.rst', '.md']

Build fails with the above error in 1.8.1, succeeds with 1.7.9.

Relates

• Close #1431: latex: Add alphanumeric enumerated list support #5001 introduced use of these values in 1.8, causing latex/pdf builds to fail for any doc with enumerated lists in markdown

[codecov]

Codecov Report

Merging #5490 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #5490      +/-   ##
==========================================
+ Coverage   83.02%   83.02%   +<.01%     
==========================================
  Files         291      291              
  Lines       38857    38859       +2     
  Branches     5845     5845              
==========================================
+ Hits        32262    32264       +2     
  Misses       5225     5225              
  Partials     1370     1370

Impacted Files	Coverage Δ
sphinx/writers/latex.py	84.13% <100%> (+0.02%)	⬆️

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[hsiaoyi0504]

I have met the same issue.

[tk0miya]

Thank you for your contribution!

[tk0miya]

I cherry-picked this to 1.8 branch manually.

[hsiaoyi0504]

@tk0miya Will this present in next release ?

[tk0miya]

Yes. This will be contained in 1.8.2.