diff -r be3584712b20 -r 2312e70cf78b mercurial/transaction.py
--- a/mercurial/transaction.py	Sat Jun 24 21:01:28 2017 -0700
+++ b/mercurial/transaction.py	Sat Jun 24 21:13:48 2017 -0700
@@ -292,6 +292,12 @@
         # but for bookmarks that are handled outside this mechanism.
         self._filegenerators[genid] = (order, filenames, genfunc, location)
 
+    @active
+    def removefilegenerator(self, genid):
+        """reverse of addfilegenerator, remove a file generator function"""
+        if genid in self._filegenerators:
+            del self._filegenerators[genid]
+
     def _generatefiles(self, suffix='', group=gengroupall):
         # write files registered for generation
         any = False