scipy/scipy — pull request #2619 by WarrenWeckesser (2013-07-06 17:04:47+00:00)
Title: BUG: stats: Handle mu=0 correctly in poisson.pmf. Closes gh-2618.

This PR should close gh-2618. The issue was fixed by changing `k*log(mu)` to `special.xlogy(k, mu)`, and by allowing mu=0 as an argument.