diff -r 5d92107dfb9b -r 1527ffe65f9f mercurial/localrepo.py
--- a/mercurial/localrepo.py	Wed Mar 15 00:28:58 2017 -0700
+++ b/mercurial/localrepo.py	Wed Mar 15 00:29:09 2017 -0700
@@ -691,11 +691,11 @@
             return
 
         try:
-            fp = self.wfile('.hgtags', 'rb+')
+            fp = self.wvfs('.hgtags', 'rb+')
         except IOError as e:
             if e.errno != errno.ENOENT:
                 raise
-            fp = self.wfile('.hgtags', 'ab')
+            fp = self.wvfs('.hgtags', 'ab')
         else:
             prevtags = fp.read()