plotly/python-api — pull request #122 by theengineear (2014-09-22 06:01:37+00:00)
Title: This is an incomplete fix, but a reasonable one for now.

Basically, mpl has its own datetime system, where it uses floating
point versions of the Gregorian calendar days. My attempt to use
ISO formatted date-time strings failed. Therefore, I'm actually
manually formatting the time-string based on epoch time after
converting from mpl_date -> epoch time. Whew!