bug#29608: python.el movement functions

[Alex Branham]

Python movement statements do not always result in the behavior I'd expect. 
Consider this python file (with (|) representing point):

(|)for i in [1, 2, 3]:
    print(i)

I'd expect M-x python-nav-forward-statement to result in

for i in [1, 2, 3]:
    print(i)
(|)

but instead you wind up with

for i in [1, 2, 3]:
    (|)print(i)

and python-nav-forward-block (bound to M-e) is even worse. It results in point 
not moving at all:

(|)for i in [1, 2, 3]:
    print(i)