git-codereview: Github URL can be ssh based

The remote URL can be something like git@github.com:zimmski/review.git
and then it is not detected that a github repository is used.

Change-Id: I0e43b7eed2f8d76d2d80ecf415ceee2df25b9254
Reviewed-on: https://go-review.googlesource.com/2975
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/git-codereview/api.go b/git-codereview/api.go
index 6ab65b1..0e8bc13 100644
--- a/git-codereview/api.go
+++ b/git-codereview/api.go
@@ -43,7 +43,7 @@
 	// Gerrit must be set as Git's origin remote.
 	origin := trim(cmdOutput("git", "config", "remote.origin.url"))
 
-	if strings.Contains(origin, "//github.com/") {
+	if strings.Contains(origin, "github.com") {
 		dief("git origin must be a Gerrit host, not GitHub: %s", origin)
 	}