[Docutils-develop] alltests.py fail if recommonmark not found

[Guenter M. <mi...@us...>]

Dear Adam,

trying the test suite on an installation without recommonmark, I stumbled
about a new problem:
    
    Traceback (most recent call last):
      File "/usr/local/src/docutils-git-svn/docutils/test/test_parsers/test_recommonmark/__init__.py", line 14, in <module>
        import recommonmark
    ModuleNotFoundError: No module named 'recommonmark'
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
    […]
      File "/usr/local/src/docutils-git-svn/docutils/test/test_parsers/test_recommonmark/__init__.py", line 17, in <module>
        raise unittest.SkipTest(f'Cannot test "{md_parser}". '
    unittest.case.SkipTest: Cannot test "recommonmark". Parser not found.

It seems raising SkipTest is only applicable for test run through the
unittest framework (where I am not sure all test run).

Günter