fsmonitor: make _hashignore compatible with Python 3

The Hasher wants a bytes but we were feeding it a str. Let's
use our repr() implementation to return bytes.

In addition, the hexdigest() would return a str, which would be
compared against a bytes and would always fail. Normalize to
bytes so the compare works.

Differential Revision: https://phab.mercurial-scm.org/D7209

hgext/fsmonitor/__init__.py

@@ -236,8 +236,8 b' def _hashignore(ignore):'
 
     """
     sha1 = hashlib.sha1()
-    sha1.update(repr(ignore))
-    return sha1.hexdigest()
+    sha1.update(pycompat.byterepr(ignore))
+    return pycompat.sysbytes(sha1.hexdigest())
 
 
 _watchmanencoding = pywatchman.encoding.get_local_encoding()