It seems pip distinguishes paths with .. or extra / for constraints.
For example, the following directories are considered different.
/path/to/dir
/path/to//dir
/path/to/dir/subdir/..
This commit tries to normalize the given directory name to avoid
"Could not satisfy constraints for 'xxxx': installation from path
or url cannot be constrained to a version" error due to directory
name mismatch.
Reference: https://github.com/pypa/pip/pull/3582
Closes-Bug: #1542545
Change-Id: Iae9d58c27d3b10bca16e4a471507c4d5c16439a0