Itseez/opencv — pull request #2900 by atomicfusion (2014-06-26 18:38:07+00:00)
Title: Check sure that we're not already below required leaf false alarm rate before continuing to get negative samples.

It seems as though if the existing stages of a classifier were perfect, then fillPassedSamples would either hang forever or run out of negatives to draw on and fail, despite the fact that a perfect classifier has an leaf false alarm rate of zero.