remotefilelog: implement __bool__ as well as __nonzero__ for py3

Differential Revision: https://phab.mercurial-scm.org/D5601

hgext/remotefilelog/remotefilelog.py

@@ -196,6 +196,8 b' class remotefilelog(object):'
     def __nonzero__(self):
         return True
 
+    __bool__ = __nonzero__
+
     def __len__(self):
         if self.filename == '.hgtags':
             # The length of .hgtags is used to fast path tag checking.