Using sys.exit(main()) instead of main()

TrivialFix: Similar [1] in Kolla project
As we known, Exceptions are raised by the sys.exit() function. When they
are not handled, no stack traceback is printed in the Python interpreter.
Therefore, when using sys.exit(main()) instead of main()
may be more readable and reasonable.

[1] https://review.openstack.org/#/c/349353/

Change-Id: Ic71d4bfb1085c68ea9eb7e1382e7263a81634ad1

mistral/cmd/launch.py

@@ -247,4 +247,4 @@ def main():
 
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())

mistral/db/sqlalchemy/migration/cli.py

@@ -21,6 +21,7 @@ from alembic import util as alembic_u
 from oslo_config import cfg
 from oslo_utils import importutils
 import six
+import sys
 
 from mistral.services import action_manager
 from mistral.services import workflows
@@ -129,4 +130,4 @@ def main():
     CONF.command.func(config, CONF.command.name)
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())

mistral/engine/rpc_backend/kombu/examples/client.py

@@ -12,6 +12,8 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 
+import sys
+
 from mistral.engine.rpc_backend.kombu import kombu_client
 
 
@@ -39,4 +41,4 @@ def main():
 
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())

mistral/engine/rpc_backend/kombu/examples/server.py

@@ -12,6 +12,8 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 
+import sys
+
 from mistral.engine.rpc_backend.kombu import kombu_server
 
 
@@ -48,4 +50,4 @@ def main():
 
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())

tools/sync_db.py

@@ -12,6 +12,8 @@
 #    See the License for the specific language governing permissions and
 #    limitations under the License.
 
+import sys
+
 import keystonemiddleware.opts as keystonemw_opts
 from oslo_config import cfg
 from oslo_log import log as logging
@@ -49,4 +51,4 @@ def main():
 
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())