diff -r c0d0fd87ba7c -r bbd240f81ac5 mercurial/hook.py
--- a/mercurial/hook.py	Sat Apr 07 21:21:03 2018 +0900
+++ b/mercurial/hook.py	Sat Apr 07 21:23:42 2018 +0900
@@ -154,7 +154,7 @@
     ui.log('exthook', 'exthook-%s: %s finished in %0.2f seconds\n',
            name, cmd, duration)
     if r:
-        desc, r = procutil.explainexit(r)
+        desc = procutil.explainexit(r)
         if throw:
             raise error.HookAbort(_('%s hook %s') % (name, desc))
         ui.warn(_('warning: %s hook %s\n') % (name, desc))