syz-cluster: support branch checkout in build-step

During smoke builds, we may have a tree name/branch name pair instead of
just a commit hash, which is the case for normal kernel build requests.

Support both types of requests.

Author: a-nogikh

syz-cluster/pkg/triage/git.go

@@ -30,7 +30,15 @@ func NewGitTreeOps(dir string, sandbox bool) (*GitTreeOps, error) {
 
 func (ops *GitTreeOps) HeadCommit(tree *api.Tree) (*vcs.Commit, error) {
 	// See kernel-disk/cron.yaml.
-	return ops.Commit(tree.Name + "-head")
+	return ops.Git.Commit(tree.Name + "-head")
+}
+
+func (ops *GitTreeOps) Commit(treeName, commitOrBranch string) (*vcs.Commit, error) {
+	// See kernel-disk/cron.yaml.
+	if vcs.CheckCommitHash(commitOrBranch) {
+		return ops.Git.Commit(commitOrBranch)
+	}
+	return ops.Git.Commit(treeName + "/" + commitOrBranch)
 }
 
 func (ops *GitTreeOps) ApplySeries(commit string, patches [][]byte) error {

syz-cluster/workflow/build-step/main.go

@@ -186,7 +186,7 @@ func checkoutKernel(tracer debugtracer.DebugTracer, req *api.BuildRequest, serie
 	if err != nil {
 		return nil, err
 	}
-	commit, err := ops.Commit(req.CommitHash)
+	commit, err := ops.Commit(req.TreeName, req.CommitHash)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get commit info: %w", err)
 	}
@@ -197,7 +197,7 @@ func checkoutKernel(tracer debugtracer.DebugTracer, req *api.BuildRequest, serie
 	if len(patches) > 0 {
 		tracer.Log("applying %d patches", len(patches))
 	}
-	err = ops.ApplySeries(req.CommitHash, patches)
+	err = ops.ApplySeries(commit.Hash, patches)
 	return commit, err
 }