fix: revert git clone http redirection forbidden (#38530)

Revert to 1.26 behavior.

Incomplete, HandleGitCmdHTTPRedirection can be improved

modules/git/redirection.go

@@ -0,0 +1,15 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package git
+
+import "gitea.dev/modules/git/gitcmd"
+
+func HandleGitCmdHTTPRedirection(cmd *gitcmd.Command, targets ...string) {
+	// Protect from SSRF vector (e.g. migrating from an attacker URL).
+	// cmd.AddConfig("http.followRedirects", "false")
+	// However, we can't do so at the moment:
+	// this fails due to 301: git -c http.followRedirects=false clone -v https://gitlab.com/{owner}/{repo}
+	// this succeeds: git -c http.followRedirects=false clone -v https://gitlab.com/{owner}/{repo}.git
+	// FIXME: GIT-CLONE-HTTP-REDIRECT-SSRF: need a complete solution in the future
+}

modules/git/repo.go

@@ -151,9 +151,7 @@ func Clone(ctx context.Context, from, to string, opts CloneRepoOptions) error {
 	}
 
 	cmd := gitcmd.NewCommand().AddArguments("clone")
-	// Never follow HTTP redirects: no clone caller needs them, and a remote redirecting to an
-	// otherwise-blocked address would be an SSRF vector (e.g. migrating from an attacker URL).
-	cmd.AddArguments("-c", "http.followRedirects=false")
+	HandleGitCmdHTTPRedirection(cmd, from, to)
 	if opts.SkipTLSVerify {
 		cmd.AddArguments("-c", "http.sslVerify=false")
 	}

modules/git/repo_test.go

@@ -26,6 +26,7 @@ func TestRepoIsEmpty(t *testing.T) {
 // TestCloneRefusesRedirects ensures Clone never follows HTTP redirects, so a remote
 // cannot redirect to an otherwise-blocked address (SSRF, e.g. during migration).
 func TestCloneRefusesRedirects(t *testing.T) {
+	t.Skip("FIXME: GIT-CLONE-HTTP-REDIRECT-SSRF: need a complete solution in the future")
 	var targetHit atomic.Bool
 	target := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		targetHit.Store(true)