Bug 1178955 - Print config path on failure; r=smacleod

Actionable error messages are useful.

--HG--
extra : commitid : CDhGEzOJpTk
extra : rebase_source : cb90b3c4c39cc502a4680c1b71fb69b316443688
extra : amend_source : 8f21e837c34138a807f6a8afeefa233e96c56880

tools/mercurial/hgsetup/wizard.py

@@ -222,12 +222,13 @@ class MercurialSetupWizard(object):
         try:
             c = MercurialConfig(config_path)
         except ConfigObjError as e:
-            print('Error importing existing Mercurial config!\n')
+            print('Error importing existing Mercurial config: %s\n' % config_path)
             for error in e.errors:
                 print(error.message)
 
             return 1
         except HgIncludeException as e:
+            print('Error importing existing Mercurial config: %s\n' % config_path)
             print(e.message)
 
             return 1