cmd/golangorg: fix go.dev in go-discovery

I had hoped go.dev would be running in golang-org by this point in the stack,
but it needs to keep running in go-discovery for a little bit longer.
Make that work.

Change-Id: I5e2c155e6b118ef474758fd443d519ea351bd86b
Reviewed-on: https://go-review.googlesource.com/c/website/+/342898
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
diff --git a/cmd/golangorg/godevapp.yaml b/cmd/golangorg/godevapp.yaml
index a93e566..b77db6c 100644
--- a/cmd/golangorg/godevapp.yaml
+++ b/cmd/golangorg/godevapp.yaml
@@ -2,6 +2,9 @@
 service: go-dev
 main: ./cmd/golangorg
 
+env_variables:
+  GODEV_IN_GO_DISCOVERY: true
+
 handlers:
   - url: /.*
     secure: always
diff --git a/cmd/golangorg/server.go b/cmd/golangorg/server.go
index 54f3c86..97be166 100644
--- a/cmd/golangorg/server.go
+++ b/cmd/golangorg/server.go
@@ -99,8 +99,14 @@
 
 	handler := NewHandler(*contentDir, *goroot)
 
-	handler = webtest.HandlerWithCheck(handler, "/_readycheck",
-		filepath.Join(*contentDir, "../cmd/golangorg/testdata/*.txt"))
+	if os.Getenv("GODEV_IN_GO_DISCOVERY") != "" {
+		// Running in go-discovery for a little longer, do not expect the golang-org prod setup.
+		handler = webtest.HandlerWithCheck(handler, "/_readycheck",
+			filepath.Join(*contentDir, "../cmd/golangorg/testdata/godev.txt"))
+	} else {
+		handler = webtest.HandlerWithCheck(handler, "/_readycheck",
+			filepath.Join(*contentDir, "../cmd/golangorg/testdata/*.txt"))
+	}
 
 	if *verbose {
 		log.Printf("golang.org server:")
@@ -301,6 +307,12 @@
 func appEngineSetup(site *web.Site, mux *http.ServeMux) {
 	googleAnalytics = os.Getenv("GOLANGORG_ANALYTICS")
 
+	log.Printf("GODEV_IN_GO_DISCOVERY %q PROJECT %q", os.Getenv("GODEV_IN_GO_DISCOVERY"), os.Getenv("PROJECT_ID"))
+	if os.Getenv("GODEV_IN_GO_DISCOVERY") != "" {
+		// Running in go-discovery for a little longer, do not expect the golang-org prod setup.
+		return
+	}
+
 	ctx := context.Background()
 
 	datastoreClient, err := datastore.NewClient(ctx, "")