Use the canonicalize_name function for finding .dist-info

[dstufft]

Fixes #3793

[xavfernandez]

Maybe we should directly add a canonical_name property to InstallRequirement ?

[yarko]

this fixes installation; but now the problem is uninstall:

foo.bar-version installs (and *.dist-info), but during uninstall,
req/req_install.py:InstallRequirement.check_if_exists() tries to find:

self.req, where self.req.name == foo_bar,

and pkg_resources.get_distribution() will find foo.bar, but not foo_bar (nor foo-bar);

Probably need to look at _vendor/pkg_resources/init.py: WorkingSet.resolve();
Wasn't immediately clear to me what what / where would fix this...

[yarko]

Update:

pip list will produce "foo.bar" as an installed package;
pip uninstall foo.bar seems to work ok, so maybe this is not a problem
even though its a bit confusing, because at code level you're doing things like:

from foo_bar import something

[pradyunsg]

(to notify people) +1 to @xavfernandez's idea.

[xavfernandez]

@dstufft Maybe add a changelog for the #3793 issue ?