Passing a transposed array to patch.set_offsets() #7785

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###Bug report

Bug summary
The method patch.set_offsets() fails quietly if passed a transposed array compared to what it expects.

Code for reproduction

import scipy
from matplotlib import pyplot as plt

U = scipy.rand(2,10)
patch = plt.scatter(U[0, :], U[1, :])
U[0, :] = 0
patch.set_offsets(U)
plt.show()

Actual outcome

A figure with 5 scattered points at the origin and 5 scattered in the box [0,1]x[0,1]

Expected outcome

I expect this to fail, the array U should be Nx2, rather than 2xN

Matplotlib version

Python 2.7.11 |Anaconda 2.4.1 (x86_64)| (default, Dec 6 2015, 18:57:58) (MacOSX)
Matplotlib version: 1.5.1