--- a/mercurial/revlog.py	Tue Sep 03 23:45:38 2019 +0200
+++ b/mercurial/revlog.py	Fri Sep 27 16:40:07 2019 +0200
@@ -1861,6 +1861,7 @@
 
         if sidedata is None:
             sidedata = {}
+            flags = flags & ~REVIDX_SIDEDATA
         elif not self.hassidedata:
             raise error.ProgrammingError(
                 _("trying to add sidedata to a revlog who don't support them")