avisynth 2.5.2, crop at non multiple of 4, shows no error

[nuked]

I'm working with interlaced material in YV12. doing this:

crop(0,106,712,268)

makes bad things happen.
The height is a multiple of 4 but the top boundary is not. This makes colors get all mixed up between fields in a real bad way. The manual kinda explains..

"In YV12:
width mod-2
height mod-2 if video is progressive
height mod-4 if video is interlaced "

but is vague at best... my height is a multiple of 4... the top boudary is not.

If I do everyhthing as mutliples of 4 I have no problem.
If I make my height a multiple of 2 I get an error. And this seems good. It doesn't know I have interlaced content so I don't know how it knows the 4 pixel restriction aplies and not the 2 (because I have avisynth in field based mode maybe?) but anyway it does and that's good. It seems though it should also produce an error on this though:

crop(0,106,712,268)

because certainly te results are not good. Sorry if this has been brought up but the search engine doesn't take "2" or "4".

[Richard Berg]

While we've made some improvements in this area, I don't think IT_FIELDBASED is reliable enough to depend on. The fix would be easy enough, but I'll wait on sh0dan to weigh in before changing anything.

[nuked]

Actually I am not in field based mode when cropping, I just checked. After running telecide it is still not in field based mode but problems show up. I can also see the problems by running separtefields() which of course does end up in field based mode... any which way though the crop itself is not field based if it matters, but later operations are needing to be able to operate on the fields.