有人能解释这种超几何分布在scipy中的奇怪行为吗?

I am running Python 2.6.5 on Mac OS X 10.6.4 (this is not the native version, I installed it myself) with Scipy 0.8.0. If I do the following:I am running Python 2.6.5 on Mac OS X 10.6.4 (t