pydata/pandas — pull request #1731 by ivanov (2012-08-04 22:18:09+00:00)
Title: DOC: skipna not an argument of drop_duplicates

From what I can tell, `skipna` keyword was both added and subsequently
removed in #1244. However, the docstring for DataFrame.drop_duplicates
still lists it as a parameter.

I remove this from the docs, so they accurately represent the code.
An alternative to this would be to put back the skipna functionality.

pinging @changhiskhan, since he was the one that worked on this.