fix: do not update cached actions with stale origin URL (#1014)

## Background

Remote action cache directories can be keyed by the raw `uses` string. When Gitea's `DEFAULT_ACTIONS_URL` changes, the raw `uses` value may stay the same while the resolved clone URL changes.

In that case, an existing cached clone can still point to the old `origin` URL. Reusing it may fetch from the wrong remote with credentials for the new resolved URL, causing action clone failures until the user manually clears `~/.cache/act`.

## Changes

- Verify the cached clone's `origin` URL before reusing it in `CloneIfRequired`.
- Remove the cached clone and re-clone when the existing `origin` is different from the requested URL.

## Related

- Fixes #1010

Reviewed-on: https://gitea.com/gitea/runner/pulls/1014
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Zettat123 <39446+zettat123@noreply.gitea.com>
Co-committed-by: Zettat123 <39446+zettat123@noreply.gitea.com>

act/common/git/git.go

@@ -265,8 +265,23 @@ type NewGitCloneExecutorInput struct {
 func CloneIfRequired(ctx context.Context, refName plumbing.ReferenceName, input NewGitCloneExecutorInput, logger log.FieldLogger) (*git.Repository, bool, error) {
 	r, err := git.PlainOpen(input.Dir)
 	if err == nil {
-		// Reuse existing clone
-		return r, true, nil
+		// Verify the cached clone still points to the resolved URL before reusing it.
+		remote, err := r.Remote("origin")
+		if err == nil && len(remote.Config().URLs) > 0 && remote.Config().URLs[0] == input.URL {
+			// Reuse existing clone
+			return r, true, nil
+		}
+
+		if err != nil {
+			logger.Debugf("Removing cached clone at %s because origin cannot be read: %v", input.Dir, err)
+		} else if len(remote.Config().URLs) == 0 {
+			logger.Debugf("Removing cached clone at %s because origin has no URL", input.Dir)
+		} else {
+			logger.Debugf("Removing cached clone at %s because origin URL changed from %s to %s", input.Dir, remote.Config().URLs[0], input.URL)
+		}
+		if err := os.RemoveAll(input.Dir); err != nil {
+			return nil, false, fmt.Errorf("remove cached clone %s: %w", input.Dir, err)
+		}
 	}
 
 	var progressWriter io.Writer

act/common/git/git_test.go

@@ -235,6 +235,51 @@ func TestGitCloneExecutor(t *testing.T) {
 	}
 }
 
+func TestGitCloneExecutorReclonesWhenOriginURLChanges(t *testing.T) {
+	createRemote := func(message string) string {
+		remoteDir := t.TempDir()
+		require.NoError(t, gitCmd("init", "--bare", "--initial-branch=main", remoteDir))
+
+		workDir := t.TempDir()
+		require.NoError(t, gitCmd("clone", remoteDir, workDir))
+		require.NoError(t, gitCmd("-C", workDir, "checkout", "-b", "main"))
+		require.NoError(t, gitCmd("-C", workDir, "commit", "--allow-empty", "-m", message))
+		require.NoError(t, gitCmd("-C", workDir, "push", "-u", "origin", "main"))
+
+		return remoteDir
+	}
+
+	oldRemoteDir := createRemote("old-action")
+	newRemoteDir := createRemote("new-action")
+	cacheDir := t.TempDir()
+
+	require.NoError(t, NewGitCloneExecutor(NewGitCloneExecutorInput{
+		URL: oldRemoteDir,
+		Ref: "main",
+		Dir: cacheDir,
+	})(t.Context()))
+
+	markerPath := filepath.Join(cacheDir, "stale-marker")
+	require.NoError(t, os.WriteFile(markerPath, []byte("stale"), 0o644))
+
+	require.NoError(t, NewGitCloneExecutor(NewGitCloneExecutorInput{
+		URL: newRemoteDir,
+		Ref: "main",
+		Dir: cacheDir,
+	})(t.Context()))
+
+	originURL, err := findGitRemoteURL(t.Context(), cacheDir, "origin")
+	require.NoError(t, err)
+	assert.Equal(t, newRemoteDir, originURL)
+
+	out, err := exec.Command("git", "-C", cacheDir, "log", "--oneline", "-1", "--format=%s").Output()
+	require.NoError(t, err)
+	assert.Equal(t, "new-action", strings.TrimSpace(string(out)))
+
+	_, err = os.Stat(markerPath)
+	require.True(t, os.IsNotExist(err), "stale cached directory should be removed before recloning")
+}
+
 func TestGitCloneExecutorNonFastForwardRef(t *testing.T) {
 	// Simulate the scenario where a remote ref (e.g. a GitHub PR head ref) changes
 	// non-fast-forward between two fetches. Before the fix, the fetch used Force=false,