diff -r 0132221c25cd -r 876494fd967d mercurial/changegroup.py
--- a/mercurial/changegroup.py	Mon Sep 24 14:46:37 2018 -0700
+++ b/mercurial/changegroup.py	Thu Jan 17 09:17:12 2019 -0800
@@ -275,7 +275,7 @@
             # because we need to use the top level value (if they exist)
             # in this function.
             srctype = tr.hookargs.setdefault('source', srctype)
-            url = tr.hookargs.setdefault('url', url)
+            tr.hookargs.setdefault('url', url)
             repo.hook('prechangegroup',
                       throw=True, **pycompat.strkwargs(tr.hookargs))