store: add a fallback _pathencode Python function

which does the equivalent of parsers.pathencode, so it can be used as a
default

mercurial/store.py

@@ -254,19 +254,23 b' def _hybridencode(path, dotencode):'
         res = _hashencode(path, dotencode)
     return res
 
-def _plainhybridencode(f):
-    return _hybridencode(f, False)
+def _pathencode(path):
+    ef = _encodefname(encodedir(path)).split('/')
+    res = '/'.join(_auxencode(ef, True))
+    if len(res) > _maxstorepathlen:
+        return None
+    return res
 
-_pathencode = getattr(parsers, 'pathencode', None)
-if _pathencode:
+_pathencode = getattr(parsers, 'pathencode', _pathencode)
+
     def _dothybridencode(f):
         ef = _pathencode(f)
         if ef is None:
             return _hashencode(encodedir(f), True)
         return ef
-else:
-    def _dothybridencode(f):
-        return _hybridencode(f, True)
+
+def _plainhybridencode(f):
+    return _hybridencode(f, False)
 
 def _calcmode(path):
     try: