git-codereview: work around compiler bug

Using the 'return &gitTest{...}' form the gt variable is not
set during the deferred func execution, causing the tmp dir
to be removed always, making all the tests fail.

Issue golang/go#9738.

Change-Id: Iac91926ea5d756547eaade52effe68bc7706c17a
Reviewed-on: https://go-review.googlesource.com/3620
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
diff --git a/git-codereview/util_test.go b/git-codereview/util_test.go
index 8197867..cd62f33 100644
--- a/git-codereview/util_test.go
+++ b/git-codereview/util_test.go
@@ -130,12 +130,13 @@
 		t.Fatal(err)
 	}
 
-	return &gitTest{
+	gt = &gitTest{
 		pwd:    pwd,
 		tmpdir: tmpdir,
 		server: server,
 		client: client,
 	}
+	return gt
 }
 
 func (gt *gitTest) removeStubHooks() {