diff -r 232c88dd89e3 -r 44d84b726c8a mercurial/changegroup.py
--- a/mercurial/changegroup.py	Tue Oct 13 03:23:17 2020 +0200
+++ b/mercurial/changegroup.py	Tue Oct 06 01:51:56 2020 +0200
@@ -333,6 +333,10 @@
             clend = len(cl)
             changesets = clend - clstart
             progress.complete()
+            del deltas
+            # TODO Python 2.7 removal
+            # del efilesset
+            efilesset = None
             self.callback = None
 
             # pull off the manifest group