cmd/gopherbot: label x/pkgsite issues as go.dev

The feedback link (https://golang.org/s/discovery-feedback) was updated
to use an issue title prefix of x/pkgsite. We should label issues based
on the new prefix as well.

Fixes golang/go#41481

Change-Id: Id7615b8996c2d945d405a5996136fbb7cece42cf
Reviewed-on: https://go-review.googlesource.com/c/build/+/255939
Trust: Alexander Rakoczy <alex@golang.org>
Run-TryBot: Alexander Rakoczy <alex@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/cmd/gopherbot/gopherbot.go b/cmd/gopherbot/gopherbot.go
index ab9e30f..f1cddda 100644
--- a/cmd/gopherbot/gopherbot.go
+++ b/cmd/gopherbot/gopherbot.go
@@ -904,7 +904,7 @@
 		if strings.HasPrefix(gi.Title, "x/vgo") {
 			return b.setMilestone(ctx, gi, vgo)
 		}
-		if strings.HasPrefix(gi.Title, "go.dev:") {
+		if strings.HasPrefix(gi.Title, "go.dev:") || strings.HasPrefix(gi.Title, "x/pkgsite") {
 			return b.setMilestone(ctx, gi, unreleased)
 		}
 		return nil
@@ -954,7 +954,8 @@
 
 func (b *gopherbot) labelGoDevIssues(ctx context.Context) error {
 	return b.gorepo.ForeachIssue(func(gi *maintner.GitHubIssue) error {
-		if gi.Closed || gi.PullRequest || !strings.HasPrefix(gi.Title, "go.dev:") || gi.HasLabel("go.dev") || gi.HasEvent("unlabeled") {
+		hasGoDevTitle := strings.HasPrefix(gi.Title, "go.dev:") || strings.HasPrefix(gi.Title, "x/pkgsite")
+		if gi.Closed || gi.PullRequest || !hasGoDevTitle || gi.HasLabel("go.dev") || gi.HasEvent("unlabeled") {
 			return nil
 		}
 		return b.addLabel(ctx, b.gorepo.ID(), gi, "go.dev")