[2017.7] Fix docstring integration test failure

[rallytime]

What does this PR do?

Fixes the following test failure:

• integration.modules.test_sysmod.SysModuleTest.test_valid_docs

What issues does this PR fix or reference?

This was introduced with #44552.

[sathieu]

A similar bug is currently happening only on win2016-py2:

03:06:47        ============================  Overall Tests Report  ============================
03:06:47        *** integration.modules.test_sysmod Tests  *************************************
03:06:47         --------  Tests with Errors  --------------------------------------------------
03:06:47           -> integration.modules.test_sysmod.SysModuleTest.test_valid_docs  ...........
03:06:47        Traceback (most recent call last):
03:06:47          File "c:\users\admini~1\appdata\local\temp\kitchen\testing\tests\integration\modules\test_sysmod.py", line 29, in test_valid_docs
03:06:47            '\n'.join(['  - {0}'.format(f) for f in ret['missing_docstring']]),
03:06:47        TypeError: 'bool' object has no attribute '__getitem__'
03:06:47           .............................................................................
03:06:47         -------------------------------------------------------------------------------
03:06:47        ================================================================================
03:06:47        FAILED (total=1, skipped=0, passed=0, failures=0, errors=1) 
03:06:47        ============================  Overall Tests Report  ============================

Any idea how to fix it?