Add WithHead option to prcreator for App-auth PR creation

cmd/prcreator/main.go

@@ -61,14 +61,17 @@ func main() {
 		logrus.WithError(err).Fatal("failed to gather options")
 	}
 
+	var prOpts []prcreation.PrOption
+	prOpts = append(prOpts, prcreation.PrBody(opts.prMessage))
+	prOpts = append(prOpts, prcreation.PrAssignee(opts.prAssignee))
+	prOpts = append(prOpts, prcreation.GitCommitMessage(opts.gitCommitMessage))
+
 	if err := opts.PRCreationOptions.UpsertPR(".",
 		opts.organization,
 		opts.repo,
 		opts.branch,
 		opts.prTitle,
-		prcreation.PrBody(opts.prMessage),
-		prcreation.PrAssignee(opts.prAssignee),
-		prcreation.GitCommitMessage(opts.gitCommitMessage),
+		prOpts...,
 	); err != nil {
 		logrus.WithError(err).Fatal("failed to upsert PR")
 	}

pkg/github/prcreation/orgaware.go

@@ -0,0 +1,46 @@
+package prcreation
+
+import (
+	"strings"
+
+	"sigs.k8s.io/prow/pkg/github"
+)
+
+// OrgAwareClient wraps a github.Client so that FindIssues routes through
+// FindIssuesWithOrg. Prow's App auth round-tripper requires the org in
+// the request context to resolve the installation token, but
+// bumper.UpdatePullRequestWithLabels internally calls FindIssues which
+// passes an empty org.
+//
+// When IsAppAuth is true, BotUser() appends "[bot]" to the login so that
+// GitHub's search API author: qualifier matches the App's acting identity.
+type OrgAwareClient struct {
+	github.Client
+	Org       string
+	IsAppAuth bool
+}
+
+func (c *OrgAwareClient) FindIssues(query, sort string, asc bool) ([]github.Issue, error) {
+	return c.Client.FindIssuesWithOrg(c.Org, query, sort, asc)
+}
+
+// BotUser returns the bot user data. When the client is using GitHub App auth,
+// it appends the "[bot]" suffix to the login. GitHub Apps act as "slug[bot]"
+// users, but prow's getUserData only stores the bare slug. The search API's
+// author: qualifier requires the full "slug[bot]" form to match PRs created
+// by the App; using the bare slug results in a 422 because that user does not
+// exist on GitHub.
+func (c *OrgAwareClient) BotUser() (*github.UserData, error) {
+	user, err := c.Client.BotUser()
+	if err != nil {
+		return nil, err
+	}
+	if !c.IsAppAuth || strings.HasSuffix(user.Login, "[bot]") {
+		return user, nil
+	}
+	return &github.UserData{
+		Name:  user.Name,
+		Login: user.Login + "[bot]",
+		Email: user.Email,
+	}, nil
+}