Bug report

Bug summary

Error in the coordinates in class FancyArrow for shape 'full', original code is

coords = np.concatenate([left_half_arrow[:-2],
                                             right_half_arrow[-2::-1]])

resulting in a triangle-like arrow tail. Code should be

coords = np.concatenate([left_half_arrow[:-1],
                                             right_half_arrow[-2::-1]])

Actual outcome

Expected outcome

Matplotlib version

matplotlib version 2.0.0, Linux, pip

Notes
I know that FancyArrow will be deprecated and replaced by FancyArrowPatch. However, FancyArrowPatch does not allow to directly set the arrow head dimensions (width and length) in data coordinates, only in display coordinates (points). It would be nice to be able to set the arrow dimensions also in data coordinates in FancyArrowPatch.