Paste over siso/nativelink connection issues

siso.diff

diff --git a/go/src/infra/build/siso/auth/cred/credhelper.go b/go/src/infra/build/siso/auth/cred/credhelper.go
index 16d173e978..2b6179de21 100644
--- a/go/src/infra/build/siso/auth/cred/credhelper.go
+++ b/go/src/infra/build/siso/auth/cred/credhelper.go
@@ -158,7 +158,7 @@ func (h *credHelper) token(endpoint string) (*oauth2.Token, error) {
        }
        auth := prc.headers["authorization"]
        if auth == "" {
-               return nil, fmt.Errorf("no Authorization in resp from helper %s: %w\nstdout: %s", h.path, err, string(prc.stdout))
+               auth = "Bearer "
        }
        token := strings.TrimSpace(strings.TrimPrefix(auth, "Bearer "))
        t := &oauth2.Token{
diff --git a/go/src/infra/build/siso/reapi/reapi.go b/go/src/infra/build/siso/reapi/reapi.go
index 4c2e339aea..e408a3769c 100644
--- a/go/src/infra/build/siso/reapi/reapi.go
+++ b/go/src/infra/build/siso/reapi/reapi.go
@@ -92,7 +92,7 @@ func (o *Option) RegisterFlags(fs *flag.FlagSet, envs map[string]string) {
 
 // UpdateProjectID updates the Option for projID and returns cloud project ID to use.
 func (o *Option) UpdateProjectID(projID string) string {
-       if projID != "" && !strings.HasPrefix(o.Instance, "projects/") {
+       if projID != "" && !strings.HasPrefix(o.Instance, "projects/") && o.Instance != "intentionally_left_blank" {
                o.Instance = path.Join("projects", projID, "instances", o.Instance)
        }
        if projID == "" && strings.HasPrefix(o.Instance, "projects/") {
@@ -209,6 +209,9 @@ func New(ctx context.Context, cred cred.Cred, opt Option) (*Client, error) {
        if opt.Instance == "" {
                return nil, errors.New("no reapi instance")
        }
+       if opt.Instance == "intentionally_left_blank" {
+               opt.Instance = ""
+       }
        clog.Infof(ctx, "address: %q instance: %q", opt.Address, opt.Instance)
        conn, err := newConn(ctx, opt.Address, cred, opt)
        if err != nil {