contrib: fix check-code to be able to detect missing _() with bytestrings

Differential Revision: https://phab.mercurial-scm.org/D6997

contrib/check-code.py

@@ -508,7 +508,7 b' pypats = ['
          [ \t\n#]*
          (?# any strings/comments might precede a string, which
            # contains translatable message)
-         ((['"]|\'\'\'|""")[ \npq%bAPMxno]*(['"]|\'\'\'|""")[ \t\n#]+)*
+         b?((['"]|\'\'\'|""")[ \npq%bAPMxno]*(['"]|\'\'\'|""")[ \t\n#]+)*
          (?# sequence consisting of below might precede translatable message
            # - formatting string: "% 10s", "%05d", "% -3.2f", "%*s", "%%" ...
            # - escaped character: "\\", "\n", "\0" ...