tests/test-revlog-raw.py.out

grep: convert an exception to bytes for a warning message

Caught by pytype:

    File "/mnt/c/Users/Matt/hg/mercurial/commands.py", line 3457, in grep: Function _bytestr.__init__ was called with the wrong arguments [wrong-arg-types]
             Expected: (self, ints: Iterable[int])
      Actually passed: (self, ints: re.error)
      The following methods aren't implemented on re.error:
      __iter__

Differential Revision: https://phab.mercurial-scm.org/D10173

local test passed
addgroupcopy test passed
clone test passed
lowlevelcopy test passed
slicing test passed
issnapshot test passed
findsnapshot test passed