grid_from_bounding_box generates points outside the bounding box

[braingram]

Here's a relatively minimal example:

>>  gwcs.grid_from_bounding_box([[0, 5], [0, 5]], step=2, center=False)
array([[[0, 2, 4, 6],
        [0, 2, 4, 6],
        [0, 2, 4, 6],
        [0, 2, 4, 6]],

       [[0, 0, 0, 0],
        [2, 2, 2, 2],
        [4, 4, 4, 4],
        [6, 6, 6, 6]]])
>> gwcs.grid_from_bounding_box([[0, 5], [0, 5]], step=2, center=True)
array([[[0., 2., 4., 6.],
        [0., 2., 4., 6.],
        [0., 2., 4., 6.],
        [0., 2., 4., 6.]],

       [[0., 0., 0., 0.],
        [2., 2., 2., 2.],
        [4., 4., 4., 4.],
        [6., 6., 6., 6.]]])

The 6s are unexpected. I'm not sure if center=False returning int64 is expected (or if center=True/False should return different values).