py3: use pycompat.bytestr so that we don't get ascii values

This fixes `hg files 'set:(**.py)'` which makes test-check-py3-compat.t able to
run on Python 3. So if you now do `python3 ./run-tests.py
test-check-py3-compat`, the test will actually run.

mercurial/fileset.py

@@ -14,6 +14,7 b' from . import ('
     error,
     merge,
     parser,
+    pycompat,
     registrar,
     scmutil,
     util,
@@ -43,6 +44,7 b' globchars = ".*{}[]?/\\\\_"'
 
 def tokenize(program):
     pos, l = 0, len(program)
+    program = pycompat.bytestr(program)
     while pos < l:
         c = program[pos]
         if c.isspace(): # skip inter-token whitespace