This fixes bug #22663 ("25.0.91; python.el electric-indent misbehaviour

with 'except:'"). Note that the bug is not restricted to "except:" but

affects all statements that are dedented by an electric colon.

For instance, entering a colon after "else" in

    if do:

        something()

        else

    outside

results in

    if do:

        something()

    else:

        outside

before the bug fix but

    if do:

        something()

    else:

    outside

after the bug fix.

-- Joel