cmd/go/internal/modfetch/gitrepo: fix fetch of tags

This is apparently another Gerrit/JGit bug:
fetch -t is supposed to be shorthand for
including refs/tags/*:refs/tags/* on the
command-line, but not for go.googlesource.com.
Avoid -t.

Change-Id: I3e6264f7cbaf3e41fa248ca7f50846ef6f4a8a02
Reviewed-on: https://go-review.googlesource.com/121299
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

vendor/cmd/go/internal/modfetch/gitrepo/fetch.go

diff --git a/vendor/cmd/go/internal/modfetch/gitrepo/fetch.go b/vendor/cmd/go/internal/modfetch/gitrepo/fetch.go
index a2f58c0..a4ee7fc 100644
--- a/vendor/cmd/go/internal/modfetch/gitrepo/fetch.go
+++ b/vendor/cmd/go/internal/modfetch/gitrepo/fetch.go
@@ -348,7 +348,7 @@
 		if len(unshallowFlag) > 0 {
 			protoFlag = []string{"-c", "protocol.version=0"}
 		}
-		if _, err := codehost.Run(r.dir, "git", protoFlag, "fetch", unshallowFlag, "-f", "-t", r.remote, "refs/heads/*:refs/heads/*"); err != nil {
+		if _, err := codehost.Run(r.dir, "git", protoFlag, "fetch", unshallowFlag, "-f", r.remote, "refs/heads/*:refs/heads/*", "refs/tags/*:refs/tags/*"); err != nil {
 			return nil, err
 		}
 	}