gosrc: Improve documentation of vcsCmd.download func signature.
diff --git a/gosrc/vcs.go b/gosrc/vcs.go
index 252047f..db0c083 100644
--- a/gosrc/vcs.go
+++ b/gosrc/vcs.go
@@ -101,7 +101,7 @@
 
 type vcsCmd struct {
 	schemes  []string
-	download func([]string, string, string, string) (string, string, error)
+	download func(schemes []string, clonePath, repo, savedEtag string) (tag, etag string, err error)
 }
 
 var vcsCmds = map[string]*vcsCmd{