hg: don't attempt to extend `sys.path` with the user site without `APPDATA`
This variable is created by the system and *should* be available, but
test-lfs-bundle.t has a test where it is explicitly unset. It wasn't caught
before because prior to 95af358fcdfe, it was limited to the py2exe binary. As a
precaution, fix both that and the pyoxidizer case that was causing the test to
fail.
Differential Revision: https://phab.mercurial-scm.org/D11354
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present