diff -r 53c265a6fc83 -r edf4fa06df94 mercurial/revlog.py
--- a/mercurial/revlog.py	Tue Oct 13 03:30:49 2020 +0200
+++ b/mercurial/revlog.py	Tue Oct 13 05:14:37 2020 +0200
@@ -2705,14 +2705,16 @@
 
             (srcrevlog, rev)
 
-        and return a triplet that control changes to sidedata content from the
+        and return a quintet that control changes to sidedata content from the
         old revision to the new clone result:
 
-            (dropall, filterout, update)
+            (dropall, filterout, update, new_flags, dropped_flags)
 
         * if `dropall` is True, all sidedata should be dropped
         * `filterout` is a set of sidedata keys that should be dropped
         * `update` is a mapping of additionnal/new key -> value
+        * new_flags is a bitfields of new flags that the revision should get
+        * dropped_flags is a bitfields of new flags that the revision shoudl not longer have
         """
         if deltareuse not in self.DELTAREUSEALL:
             raise ValueError(
@@ -2783,7 +2785,7 @@
             p2 = index[entry[6]][7]
             node = entry[7]
 
-            sidedataactions = (False, [], {})
+            sidedataactions = (False, [], {}, 0, 0)
             if sidedatacompanion is not None:
                 sidedataactions = sidedatacompanion(self, rev)
 
@@ -2792,7 +2794,11 @@
             cachedelta = None
             rawtext = None
             if any(sidedataactions) or deltareuse == self.DELTAREUSEFULLADD:
-                dropall, filterout, update = sidedataactions
+                dropall = sidedataactions[0]
+                filterout = sidedataactions[1]
+                update = sidedataactions[2]
+                new_flags = sidedataactions[3]
+                dropped_flags = sidedataactions[4]
                 text, sidedata = self._revisiondata(rev)
                 if dropall:
                     sidedata = {}
@@ -2801,6 +2807,10 @@
                 sidedata.update(update)
                 if not sidedata:
                     sidedata = None
+
+                flags |= new_flags
+                flags &= ~dropped_flags
+
                 destrevlog.addrevision(
                     text,
                     tr,