cmd/gitmirror: push to prod namespace

Overlooked this -- the set-image command doesn't use a YAML file so
needs to specify the namespace explicitly.

Change-Id: I3602dbb31afc27df6087207b57b081975024021d
Reviewed-on: https://go-review.googlesource.com/c/build/+/347411
Trust: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/cmd/gitmirror/Makefile b/cmd/gitmirror/Makefile
index 0a572de..8db9e3f 100644
--- a/cmd/gitmirror/Makefile
+++ b/cmd/gitmirror/Makefile
@@ -23,8 +23,8 @@
 	docker push $(IMAGE_STAGING):$(VERSION)
 
 deploy-prod: push-prod
-	kubectl set image deployment/gitmirror-serving-deployment gitmirror=$(IMAGE_PROD):$(VERSION)
-	kubectl set image deployment/gitmirror-mirroring-deployment gitmirror=$(IMAGE_PROD):$(VERSION)
+	kubectl set image --namespace=prod deployment/gitmirror-serving-deployment gitmirror=$(IMAGE_PROD):$(VERSION)
+	kubectl set image --namespace=prod deployment/gitmirror-mirroring-deployment gitmirror=$(IMAGE_PROD):$(VERSION)
 
 deploy-staging: push-staging
 	echo "no staging configuration"