More lenient expression for allowed version tags

cmd/syncthing/main.go

@@ -58,7 +58,7 @@ var (
 	IsRelease         bool
 	IsBeta            bool
 	LongVersion       string
-	allowedVersionExp = regexp.MustCompile(`^v\d+\.\d+\.\d+(-[a-z0-9]+)*(\.\d+)*(\+\d+-g[0-9a-f]+)?(-dirty)?$`)
+	allowedVersionExp = regexp.MustCompile(`^v\d+\.\d+\.\d+(-[a-z0-9]+)*(\.\d+)*(\+\d+-g[0-9a-f]+)?(-[^\s]+)?$`)
 )
 
 const (