Merged in svetlyak40wt/setuptools/svetlyak40wt/make-194-same-level-header-as-other-vers-1453106898145 (pull request #171)

Make 19.4 same level header as other version numbers.

Invoke import on importlib.machinery directly. Access an attribute to force import in delayed-import environments. Fixes #487.

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branch : svetlyak40wt/make-194-same-level-header-as-other-vers-1453106898145

The problem was that restructured text considered 19.4 is a sibtitle to "CHANGES".

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branch : svetlyak40wt/make-194-same-level-header-as-other-vers-1453106898145

Possible fix for #207

in sys.path.  This ensures that lookups in __path__ will be the same
as sys.path resolution.

This also adds a replace argument to Distribution.insert_on meant
to be used with the replace argumen to WorkingSet.add.  This ensures
that new sys.path entries added via WorkingSet.add are inserted at
the beginning, rather than appended to the end.  This is necessary
for consistency with the above change, and kind of makes more sense
anyways.  This means that if a Distribution is added to a WorkingSet,
that replaces a different version of that Distribution, the new version
of that Distribution will have its location first on sys.path.

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Based on experimentation, the canonical module name needs to be in sys.modules on Python prior to 3.3, but must be omitted on Python 3.3 and later.

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Pop the module off the stack, preventing the 'Version' class from having a different manifestation in packaging than in pkg_resources.

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branch : feature/issue-229