bug#21526: 24.5; prolog-mode: broken indentation for if-then-else construct

[Stefan Monnier]

> When I place point on the "a" and press TAB, the expected result is:
>
>    test :-
>            (   a
>            ;   b
>            ).
>
> However, in contrast to the prolog.el by Stefan Bruda, I get again:
>
>    test :-
>            (a
>            ;   b
>            ).

That's expected: the TAB behavior prolog.el provides only changes the
spacing at the beginning of the line, not the spacing within elements of
the line.


        Stefan