mirror_mr_pipeline: fix error when no pipeline found

This case should trigger a new pipeline instead of reporting an error.

scripts/mirror_mr_pipeline.py

@@ -85,26 +85,29 @@ def main():
     try:
         pipelines = get_pipelines(project, args.commit, "^" + args.ref)
         pipeline = pipelines[0]
-    except LookupError as e:
-        sys.exit(str(e))
-
-    # Wait for pipeline termination
-    print("Pipeline: %s" % pipeline.web_url)
-    if pipeline.status not in TERMINATED_STATES:
-        print("Waiting for completion", end="")
-        while pipeline.status not in TERMINATED_STATES:
-            print(".", end="", flush=True)
-            time.sleep(1)
-            pipeline = project.pipelines.get(pipeline.id, retry_transient_errors=True)
-        print("")
-
-    print("Result: %s" % pipeline.status, flush=True)
-
-    # Mirror result in success/failure case
-    if pipeline.status == "success":
-        sys.exit(0)
-    elif pipeline.status == "failed":
-        sys.exit(1)
+
+        # Wait for pipeline termination
+        print("Pipeline: %s" % pipeline.web_url)
+        if pipeline.status not in TERMINATED_STATES:
+            print("Waiting for completion", end="")
+            while pipeline.status not in TERMINATED_STATES:
+                print(".", end="", flush=True)
+                time.sleep(1)
+                pipeline = project.pipelines.get(
+                    pipeline.id, retry_transient_errors=True
+                )
+            print("")
+
+        print("Result: %s" % pipeline.status, flush=True)
+
+        # Mirror result in success/failure case
+        if pipeline.status == "success":
+            sys.exit(0)
+        elif pipeline.status == "failed":
+            sys.exit(1)
+
+    except LookupError:
+        pass
 
     # Else start a new pipeline on given ref
     try: