remotefilelog: honor the `--format` arg of the `debugindex` command

Flagged by PyCharm while investigating pytype spew.  The other `**opts` above
are already accessed as str.  I've never used remotefilelog, and don't have a
repo to test this on, so I'm trusting the nearby code.

hgext/remotefilelog/debugcommands.py

@@ -115,7 +115,7 b' def debugindex(orig, ui, repo, file_=Non'
     r = buildtemprevlog(repo, file_)
 
     # debugindex like normal
-    format = opts.get(b'format', 0)
+    format = opts.get('format', 0)
     if format not in (0, 1):
         raise error.Abort(_(b"unknown format %d") % format)