--- a/tests/test-commit.t	Sat Jul 29 19:12:48 2017 -0700
+++ b/tests/test-commit.t	Sun Jul 30 12:19:46 2017 +0530
@@ -138,6 +138,9 @@
   $ hg commit -m "special chars in extra" --extra id@phab=214
   abort: keys can only contain ascii letters, digits, '_' and '-'
   [255]
+  $ hg commit -m "empty key" --extra =value
+  abort: unable to parse '=value', keys can't be empty
+  [255]
   $ hg commit -m "adding extras" --extra sourcehash=foo --extra oldhash=bar
   $ hg log -r . -T '{extras % "{extra}\n"}'
   branch=default