GAE + recursion limit

I'm writing a small translator using pyparsing library v1.5.2
( and I'm using it both from command
and on Google App Engine. Recently I checked one of my samples which
perfect from CLI against GAE and it throws me "RuntimeError 'maximum
depth exceeded'".
I did some investigation and found out that recursion
limit is the same locally and inside GA (1000). I've also tested it
locally decreasing this limit to 900 but the error didn't happen.
The problem itself rises inside pyparsing lib, line 995.

Does anyone have any clue what that might be?
Why the problem is on GAE (even when run locally), when command line
run works just fine (even with recursion limit decreased)?
Thanks in advance for any help.