tests: update test-chg.t with output change

Since this part of tests is only run with chg, hence it didn't get updated
when the error message changed.

Differential Revision: https://phab.mercurial-scm.org/D9414

tests/test-chg.t

@@ -29,7 +29,7 b' ill-formed config'
   $ chg status
   $ echo '=brokenconfig' >> $HGRCPATH
   $ chg status
-  hg: parse error at * (glob)
+  config error at * =brokenconfig (glob)
   [255]
 
   $ cp $HGRCPATH.orig $HGRCPATH