nodemap: fix missing r-prefix on regular expression

Looking at this regular expression, it's pretty obvious from reading
it that it wanted to match literal ., but since the r was missing on
the pattern it was matching any character. I guess we're just lucky
nothing bad happened as a result. This was automatically fixed by
pyupgrade, but I split it out into its own change because it seemed
important.

Differential Revision: https://phab.mercurial-scm.org/D8254

mercurial/revlogutils/nodemap.py

@@ -275,7 +275,7 b' def _rawdata_filepath(revlog, docket):'
 
 def _other_rawdata_filepath(revlog, docket):
     prefix = revlog.nodemap_file[:-2]
-    pattern = re.compile(b"(^|/)%s-[0-9a-f]+\.nd$" % prefix)
+    pattern = re.compile(br"(^|/)%s-[0-9a-f]+\.nd$" % prefix)
     new_file_path = _rawdata_filepath(revlog, docket)
     new_file_name = revlog.opener.basename(new_file_path)
     dirpath = revlog.opener.dirname(new_file_path)