fix: pull request cross references (#7979)

Closes #7974.

### Tests

- I added test coverage for Go changes...
  - [x] in their respective `*_test.go` for unit tests.
  - [ ] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7979
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Robert Wolff <mahlzahn@posteo.de>
Co-committed-by: Robert Wolff <mahlzahn@posteo.de>

modules/references/references.go

@@ -460,7 +460,8 @@ func findAllIssueReferencesBytes(content []byte, links []string) []*rawReference
 			}
 			parts := strings.Split(u.EscapedPath(), "/")
 			// /user/repo/issues/3
-			if len(parts) != 5 || parts[0] != "" {
+			// /user/repo/pulls/7/files/...
+			if len(parts) < 5 || parts[0] != "" {
 				continue
 			}
 			var sep string

modules/references/references_test.go

@@ -132,6 +132,30 @@ func TestFindAllIssueReferences(t *testing.T) {
 				{203, "user4", "repo5", "203", true, XRefActionNone, nil, nil, ""},
 			},
 		},
+		{
+			"This http://gitea.com:3000/user4/repo5/pulls/202#x yes.",
+			[]testResult{
+				{202, "user4", "repo5", "202", true, XRefActionNone, nil, nil, ""},
+			},
+		},
+		{
+			"This http://gitea.com:3000/user4/repo5/pulls/202/commits yes.",
+			[]testResult{
+				{202, "user4", "repo5", "202", true, XRefActionNone, nil, nil, ""},
+			},
+		},
+		{
+			"This http://gitea.com:3000/user4/repo5/pulls/202/files yes.",
+			[]testResult{
+				{202, "user4", "repo5", "202", true, XRefActionNone, nil, nil, ""},
+			},
+		},
+		{
+			"This http://gitea.com:3000/user4/repo5/pulls/202/files#diff- yes.",
+			[]testResult{
+				{202, "user4", "repo5", "202", true, XRefActionNone, nil, nil, ""},
+			},
+		},
 		{
 			"This http://GiTeA.COM:3000/user4/repo6/pulls/205 yes.",
 			[]testResult{