--user fixes part5:  reset_env option for adding patches to sitecustomize

Updated basecommand.py such that writing to the log file doesn't fail. If...

permission is denied for writing in the specified log file the message
will be written to a temporary one.

remove "git submodule foreach" call for backwards compatibility; expect errors in pip install because old versions of git write senseless things to stderr

--user fixes part 4,  issue #440

Mock out getcwd.

File urls on Windows32 are fragile, the test doesn't actually care about
the filesystem as it's already mocking exists and isdir.

Hopefully fixes two win32 build failures.

--user fixes pt 3  Issue #493

Append documentation about comment line in requirements file format #564

Workaround for GH-556 by completely removing pkgutil stuff and replacing with a vanilla import at the top of the file.

This reverts commit 20f8ce28.

Moved src_dir back to cwd for now. build_dir is still created in the
system's temporary dir (tempfile.gettempdir()), but always as
"pip-build".

with a vanilla import at the top of the file.

This reverts commit 5004c62b.

Doesn't fix win32. Needs more work

Fix windows CI build tests.

Issue #557

On windows we can't assume os.getcwd returns url friendly format. Use
urllib pathname2url.

Remove unix line ending assumption.