dirs: convert PyString to PyBytes
PyStringObject was renamed to PyBytes in Python 3 along with the
corresponding PyString* functions and macros. PyString* doesn't
exist in Python 3. But PyBytes* is an alias to PyString in Python 2.
So rewrite PyString* to PyBytes* for Python 2/3 dual compatibility.
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ ls
a
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
B should disappear
$ ls
a