Make mpcdf_push work also when no sources have been changed

mpcdf_push.py

@@ -88,16 +88,27 @@ def do_mpcdf_push(self, subcmd, opts, *args):
               "Configure the enabled repositories first, with `osc mpcdf_enable_repositories`", file=sys.stderr)
         raise SystemExit(1)
 
-    req_id = osc.core.create_submit_request(api_url, from_project, package, dst_project=to_project,
-                                            message="Update {0} from {1}".format(package, from_project) if not opts.message else opts.message)
-    print("Submitted package {0} to {1} in request {2}".format(package, to_project, req_id))
-    if not opts.batch:
-        print("\nPLEASE review the request by 'osc request show {0} --diff', or in the web interface\n".format(req_id))
-        print("Press Ctrl-C to abort, any key to continue", end="")
-        input()
-        result = osc.core.change_request_state(api_url, req_id, 'accepted', "Accepted on the command line via 'osc mpcdf_push'")
-        print("  Accepting request {0}:".format(req_id), result)
+    req_id = None
+    try:
+        req_id = osc.core.create_submit_request(api_url, from_project, package, dst_project=to_project,
+                                                message="Update {0} from {1}".format(package, from_project) if not opts.message else opts.message)
+    except osc.core.HTTPError as e:
+        if e.code == 400:
+            if "The request contains no actions" in e.read():
+                print("No source changes found, submit request not necessary")
+        else:
+            raise e
+
+    if req_id:
+        print("Submitted package {0} to {1} in request {2}".format(package, to_project, req_id))
+        if not opts.batch:
+            print("\nPLEASE review the request by 'osc request show {0} --diff', or in the web interface\n".format(req_id))
+            print("Press Ctrl-C to abort, any key to continue", end="")
+            input()
+            result = osc.core.change_request_state(api_url, req_id, 'accepted', "Accepted on the command line via 'osc mpcdf_push'")
+            print("  Accepting request {0}:".format(req_id), result)
 
+    if not opts.batch:
         user = osc.conf.get_apiurl_usr(api_url)
         if user not in existing_maintainers:
             print("Adding you to the list of maintainers for this package")