--- a/mercurial/upgrade.py	Tue Jan 02 18:35:11 2018 +0900
+++ b/mercurial/upgrade.py	Wed Jan 10 17:24:25 2018 +0100
@@ -631,7 +631,7 @@
         deltareuse = revlog.revlog.DELTAREUSESAMEREVS
     elif 'redeltamultibase' in actions:
         deltareuse = revlog.revlog.DELTAREUSESAMEREVS
-    if 'redeltafulladd' in actions:
+    elif 'redeltafulladd' in actions:
         deltareuse = revlog.revlog.DELTAREUSEFULLADD
     else:
         deltareuse = revlog.revlog.DELTAREUSEALWAYS