Code review comment for lp:~zorba-coders/zorba/bug1082740_fn_subsequence

Other than Till's comment, I approve. I'm still a bit wary about having to add a new flag and test logic to fn:subsequence(), since that's used a lot, so if you happen to think of a way to do this without such checks that would be ideal. But, if this flag is necessary, then so be it.