simplify AppSubURL handling

Author: bohde

routers/web/repo/view_home.go

@@ -416,13 +416,8 @@ func Home(ctx *context.Context) {
 
 // HomeRedirect redirects from /tree/* to /src/* in order to maintain a similar URL structure.
 func HomeRedirect(ctx *context.Context) {
-	prefix := "/"
-	if setting.AppSubURL != "" {
-		prefix = setting.AppSubURL
-	}
-
 	url := treeRedirectURL(
-		prefix,
+		setting.AppSubURL,
 		ctx.PathParam("username"),
 		ctx.PathParam("reponame"),
 		ctx.PathParam("*"),
@@ -436,6 +431,7 @@ func HomeRedirect(ctx *context.Context) {
 func treeRedirectURL(prefix, username, reponame, remainder string) string {
 	return path.Join(
 		prefix,
+		"/", // The prefix may be an empty string, so ensure we have a preceding slash
 		url.PathEscape(username),
 		url.PathEscape(reponame),
 		"src",

routers/web/repo/view_home_test.go

@@ -19,17 +19,17 @@ func TestTreeRedirectURL(t *testing.T) {
 	cases := []testcase{
 		{
 			name:   "ref",
-			prefix: "/", username: "user2", reponame: "readme-test", remainder: "main",
+			prefix: "", username: "user2", reponame: "readme-test", remainder: "main",
 			expected: "/user2/readme-test/src/main",
 		},
 		{
 			name:   "sha",
-			prefix: "/", username: "user2", reponame: "readme-test", remainder: "fe495ea336f079ef2bed68648d0ba9a37cdbd4aa",
+			prefix: "", username: "user2", reponame: "readme-test", remainder: "fe495ea336f079ef2bed68648d0ba9a37cdbd4aa",
 			expected: "/user2/readme-test/src/fe495ea336f079ef2bed68648d0ba9a37cdbd4aa",
 		},
 		{
 			name:   "escape",
-			prefix: "/", username: "user/2%", reponame: "readme/test?", remainder: "$/&",
+			prefix: "", username: "user/2%", reponame: "readme/test?", remainder: "$/&",
 			expected: "/user%2F2%25/readme%2Ftest%3F/src/$/&",
 		},
 		{