AttributeError: 'NoneType' object has no attribute 'splitlines'

[sentry]

Sentry Issue: BOT-COMMUNITYGENERAL-4Z

AttributeError: 'NoneType' object has no attribute 'splitlines'
(6 additional frame(s) were not displayed)
...
  File "ansibullbot/triagers/plugins/docs_info.py", line 296, in get_docs_facts
    docs_only = False not in [_is_docs_only(f.raw_data) for f in iw.pr_files]
  File "ansibullbot/triagers/plugins/docs_info.py", line 296, in <listcomp>
    docs_only = False not in [_is_docs_only(f.raw_data) for f in iw.pr_files]
  File "ansibullbot/triagers/plugins/docs_info.py", line 282, in _is_docs_only
    if _is_diff_docs_only(changed_file.file_content, changed_file.patch):
  File "ansibullbot/triagers/plugins/docs_info.py", line 218, in _is_diff_docs_only
    diff = _get_diff_info(diff)
  File "ansibullbot/triagers/plugins/docs_info.py", line 94, in _get_diff_info
    diff_lines = diff_text.splitlines()