[v12.0/forgejo] fix: redirect from /{username}/{reponame}/pulls/{index} to issue if index is a issue (#8876)

**Backport:** !8874

conflict resolved by accepting the incomming hunk and removing TestIssueTimelineLabels-func

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8876
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Reviewed-by: floss4good <floss4good@noreply.codeberg.org>
Co-authored-by: zokki <zokki.softwareschmiede@gmail.com>
Co-committed-by: zokki <zokki.softwareschmiede@gmail.com>

routers/web/repo/pull.go

@@ -360,7 +360,7 @@ func getPullInfo(ctx *context.Context) (issue *issues_model.Issue, ok bool) {
 	ctx.Data["Issue"] = issue
 
 	if !issue.IsPull {
-		ctx.NotFound("ViewPullCommits", nil)
+		ctx.Redirect(issue.Link())
 		return nil, false
 	}
 

tests/integration/issue_test.go

@@ -1526,3 +1526,35 @@ func TestIssuePostersSearch(t *testing.T) {
 		assert.EqualValues(t, 1, data.Results[0].UserID)
 	})
 }
+
+func TestIssueAndPullRedirect(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	req := NewRequest(t, "GET", "/user2/repo1/issues/1")
+	MakeRequest(t, req, http.StatusOK)
+
+	req = NewRequest(t, "GET", "/user2/repo1/pulls/2")
+	MakeRequest(t, req, http.StatusOK)
+
+	req = NewRequest(t, "GET", "/user2/repo1/pulls/1")
+	resp := MakeRequest(t, req, http.StatusSeeOther)
+	assert.Equal(t, "/user2/repo1/issues/1", resp.Header().Get("Location"))
+
+	req = NewRequest(t, "GET", "/user2/repo1/pulls/1/commits")
+	resp = MakeRequest(t, req, http.StatusSeeOther)
+	assert.Equal(t, "/user2/repo1/issues/1", resp.Header().Get("Location"))
+
+	req = NewRequest(t, "GET", "/user2/repo1/pulls/1/files")
+	resp = MakeRequest(t, req, http.StatusSeeOther)
+	assert.Equal(t, "/user2/repo1/issues/1", resp.Header().Get("Location"))
+
+	req = NewRequest(t, "GET", "/user2/repo1/issues/2")
+	resp = MakeRequest(t, req, http.StatusSeeOther)
+	assert.Equal(t, "/user2/repo1/pulls/2", resp.Header().Get("Location"))
+
+	req = NewRequest(t, "GET", "/user2/repo1/issues/9999999")
+	MakeRequest(t, req, http.StatusNotFound)
+
+	req = NewRequest(t, "GET", "/user2/repo1/pulls/9999999")
+	MakeRequest(t, req, http.StatusNotFound)
+}