[ticket/12781] Template regex for IF catch too many things

PHPBB3-12781
[ticket/12781] Add tests

PHPBB3-12781
Merge pull request #2670 from Nicofuma/ticket/12781

[ticket/12781] Template regex for IF catch too many things

* Nicofuma/ticket/12781:
  [ticket/12781] Add tests
  [ticket/12781] Template regex for IF catch too many things