Color channels changed after rotation

Looks like there is a problem with color channels when rotating an image (looks like a negative)

Here's the code to reproduce

>>> import bob.ip.base
>>> from bob.io.base.test_utils import datafile
>>> import bob.io.image
>>> import bob.io.base
>>> path = datafile('grace_hopper.png', 'bob.io.image')
>>> img = bob.io.base.load(path)
>>> rotated_shape = bob.ip.base.rotated_output_shape(img, 90)
>>> rotated = numpy.ndarray(rotated_shape, dtype = numpy.float64 )
>>> bob.ip.base.rotate(image, rotated, 90)
>>> from matplotlib import pyplot
>>> pyplot.imshow(numpy.rollaxis(numpy.rollaxis(rotated, 2),2))
>>> pyplot.show()