tests: add explicit coverage for update_hash_refs from rewriteutil
I couldn't find any evidence this is covered by tests in core (but there's a
good chance I missed it). We've seen a cute bug in that code, but first
let's just cover the cases that work correctly.
Differential Revision: https://phab.mercurial-scm.org/D11231
from __future__ import absolute_import, print_function
import sys
for line in sys.stdin:
if line.lower() in ("message-id: \n", "in-reply-to: \n"):
line = line[:-2]
print(line, end="")