I filed a ticket with pandas. I'm able to replicate this with 0.5.0 and pandas master at pandas-dev/pandas@a96cd66
This code hasn't changed on our end, so something's changed in pandas or it's coming from my numpy version. I'll leave this open until it's sorted.
another possible failure with current pandas ( I don't know which versions Ralf was using)
with test error in #1134 (comment)
Should be fixed with pandas-dev/pandas#5327 I don't know about the other error. Haven't seen it yet.
Marking this 0.5.1, so I remember to close it, if possible.