Fix return code of irc_tests.py

The scripts was always returning 0 - see
https://review.openstack.org/#/c/163876/1 which should have failed since
accessbot was not updated.

Fixed with properly wrapping main.

Change-Id: Ica8b4fa28cf9ac0009443340949ff6b32ccb9dd1

tools/irc_tests.py

@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import sys
 import yaml
 
 
@@ -51,4 +52,4 @@ def main():
     return errors
 
 if __name__ == "__main__":
-    main()
+    sys.exit(main())