Fixes git repo path contractions in two situations:
1. When path obtained from `PWD` is a logical path but git libraries
return physical paths.
2. When a git repository's subdirectory is symlinked to ouside of the
repository tree.
(1) is fixed by implementing a realpath()-like function, then reparsing
the (possibly logical) `PWD` using realpath() to convert logical
components into physical ones. The physical paths are then matched
against each other.
In the case of (2), the default behavior has been changed by simply
contracting to the home directory, exactly the same as if we are not in
a repo at all. Because determining the correct contraction is not
obvious, we bail out and just pretend we are not in a repo at all.
611a754ec7