Use git url fragment to specify reference and dir context.

Signed-off-by: David Calavera <david.calavera@gmail.com>

urlutil/git.go

@@ -1,6 +1,9 @@
 package urlutil
 
-import "strings"
+import (
+	"regexp"
+	"strings"
+)
 
 var (
 	validPrefixes = []string{
@@ -8,11 +11,13 @@ var (
 		"github.com/",
 		"git@",
 	}
+
+	urlPathWithFragmentSuffix = regexp.MustCompile(".git(?:#.+)?$")
 )
 
 // IsGitURL returns true if the provided str is a git repository URL.
 func IsGitURL(str string) bool {
-	if IsURL(str) && strings.HasSuffix(str, ".git") {
+	if IsURL(str) && urlPathWithFragmentSuffix.MatchString(str) {
 		return true
 	}
 	for _, prefix := range validPrefixes {

urlutil/git_test.go

@@ -9,10 +9,15 @@ var (
 		"git@bitbucket.org:atlassianlabs/atlassian-docker.git",
 		"https://github.com/docker/docker.git",
 		"http://github.com/docker/docker.git",
+		"http://github.com/docker/docker.git#branch",
+		"http://github.com/docker/docker.git#:dir",
 	}
 	incompleteGitUrls = []string{
 		"github.com/docker/docker",
 	}
+	invalidGitUrls = []string{
+		"http://github.com/docker/docker.git:#branch",
+	}
 )
 
 func TestValidGitTransport(t *testing.T) {
@@ -35,9 +40,16 @@ func TestIsGIT(t *testing.T) {
 			t.Fatalf("%q should be detected as valid Git url", url)
 		}
 	}
+
 	for _, url := range incompleteGitUrls {
 		if IsGitURL(url) == false {
 			t.Fatalf("%q should be detected as valid Git url", url)
 		}
 	}
+
+	for _, url := range invalidGitUrls {
+		if IsGitURL(url) == true {
+			t.Fatalf("%q should not be detected as valid Git prefix", url)
+		}
+	}
 }