Backport of Tim's checkin 2.177:

Backport of Tim's checkin 2.177:

SF bug #417093: Case sensitive import: dir and .py file w/ same name
Directory containing
    Spam.py
    spam/__init__.py
Then "import Spam" caused a SystemError, because code checking for
the existence of "Spam/__init__.py" finds it on a case-insensitive
filesystem, but then bails because the directory it finds it in
doesn't match case, and then old code assumed that was still an error
even though it isn't anymore.  Changed the code to just continue
looking in this case (instead of calling it an error).  So
    import Spam
and
    import spam
both work now.