--- a/mercurial/revlog.py	Tue Sep 03 23:51:34 2019 +0200
+++ b/mercurial/revlog.py	Tue Sep 03 23:51:17 2019 +0200
@@ -1842,7 +1842,8 @@
         if flags:
             node = node or self.hash(text, p1, p2)
 
-        rawtext, validatehash = self._processflagswrite(text, flags)
+        rawtext, validatehash = self._processflagswrite(text, flags,
+                                                        sidedata=sidedata)
 
         # If the flag processor modifies the revision data, ignore any provided
         # cachedelta.