numpy/numpy — pull request #4968 by WarrenWeckesser (2014-08-15 23:31:38+00:00)
Title: BUG: io: genfromtxt did not handle filling_values=0 correctly. Closes gh-2317.

See also
http://stackoverflow.com/questions/15144352/numpy-genfromtxt-using-filling-missing-correctly
http://stackoverflow.com/questions/25334599/missing-values-not-working-with-genfromtxt