hgweb: mimetype guessing needs a unicode path

Differential Revision: https://phab.mercurial-scm.org/D1086

mercurial/hgweb/common.py

@@ -166,7 +166,7 b' def staticfile(directory, fname, req):'
             break
     try:
         os.stat(path)
-        ct = mimetypes.guess_type(path)[0] or "text/plain"
+        ct = mimetypes.guess_type(pycompat.fsdecode(path))[0] or "text/plain"
         with open(path, 'rb') as fh:
             data = fh.read()