Do not fail with bad revision on missing sync tag

But instead fallback to comparison on an empty revision string as
current revision as this does no harm.

daemon/daemon.go

@@ -354,7 +354,7 @@ func (d *Daemon) sync() jobFunc {
 			return result, err
 		}
 		syncHead, err := d.Repo.Revision(ctx, d.GitConfig.SyncTag)
-		if err != nil {
+		if err != nil && !isUnknownRevision(err) {
 			return result, err
 		}
 		var latestVerifiedRev string
@@ -805,7 +805,7 @@ func latestValidRevision(ctx context.Context, repo *git.Repo, gitConfig git.Conf
 }
 
 func verifyWorkingRepo(ctx context.Context, repo *git.Repo, working *git.Checkout, gitConfig git.Config) error {
-	if syncRevision, err := working.SyncRevision(ctx); err != nil {
+	if syncRevision, err := working.SyncRevision(ctx); err != nil && !isUnknownRevision(err) {
 		return err
 	} else if latestVerifiedRev, _, err := latestValidRevision(ctx, repo, gitConfig, syncRevision); err != nil {
 		return err
@@ -819,3 +819,9 @@ The last verified commit was %.8s. HEAD is %.8s.`, latestVerifiedRev, headRev)
 	}
 	return nil
 }
+
+func isUnknownRevision(err error) bool {
+	return err != nil &&
+		(strings.Contains(err.Error(), "unknown revision or path not in the working tree.") ||
+			strings.Contains(err.Error(), "bad revision"))
+}

daemon/sync.go

@@ -6,7 +6,6 @@ import (
 	"encoding/base64"
 	"github.com/go-kit/kit/log"
 	"github.com/pkg/errors"
-	"strings"
 	"time"
 
 	"github.com/weaveworks/flux"
@@ -388,12 +387,6 @@ func refresh(ctx context.Context, s *Sync) error {
 	return err
 }
 
-func isUnknownRevision(err error) bool {
-	return err != nil &&
-		(strings.Contains(err.Error(), "unknown revision or path not in the working tree.") ||
-			strings.Contains(err.Error(), "bad revision"))
-}
-
 func makeGitConfigHash(remote git.Remote, conf git.Config) string {
 	urlbit := remote.SafeURL()
 	pathshash := sha256.New()