lib/config: Improve debug logging around folder marker

lib/config/folderconfiguration.go

@@ -94,12 +94,10 @@ func (f *FolderConfiguration) CreateMarker() error {
 		if err != nil {
 			return err
 		}
-		if dir, err := fs.Open("."); err == nil {
-			if serr := dir.Sync(); err != nil {
-				l.Debugln("fsync %q failed: %v", ".", serr)
-			}
-		} else {
-			l.Infof("fsync %q failed: %v", ".", err)
+		if dir, err := fs.Open("."); err != nil {
+			l.Debugln("folder marker: open . failed:", err)
+		} else if err := dir.Sync(); err != nil {
+			l.Debugln("folder marker: fsync . failed:", err)
 		}
 		fs.Hide(".stfolder")
 	}