test-globalopts: make the test compatible with chg

The test fails when run with the '--chg' option. Therefore, this
commit modifies the test to make it compatible with chg.

Test Plan:
Ran 'test-globalopts.t' with and without the '--chg' option.

Differential Revision: https://phab.mercurial-scm.org/D913

tests/test-globalopts.t

@@ -263,8 +263,14 b' Testing --debug:'
 
 Testing --traceback:
 
+#if no-chg
   $ hg --cwd c --config x --traceback id 2>&1 | grep -i 'traceback'
   Traceback (most recent call last):
+#else
+Traceback for '--config' errors not supported with chg.
+  $ hg --cwd c --config x --traceback id 2>&1 | grep -i 'traceback'
+  [1]
+#endif
 
 Testing --time: