--- a/mercurial/revlog.py	Wed Sep 04 00:34:03 2019 +0200
+++ b/mercurial/revlog.py	Tue Sep 03 23:51:34 2019 +0200
@@ -1816,7 +1816,8 @@
         """
 
     def addrevision(self, text, transaction, link, p1, p2, cachedelta=None,
-                    node=None, flags=REVIDX_DEFAULT_FLAGS, deltacomputer=None):
+                    node=None, flags=REVIDX_DEFAULT_FLAGS, deltacomputer=None,
+                    sidedata=None):
         """add a revision to the log
 
         text - the revision data to add
@@ -1835,6 +1836,9 @@
             raise error.RevlogError(_("attempted to add linkrev -1 to %s")
                                     % self.indexfile)
 
+        if sidedata is None:
+            sidedata = {}
+
         if flags:
             node = node or self.hash(text, p1, p2)