bug#19812: 24.4; suggest `shell-mode' not interactive

[Juri Linkov <juri@linkov.net>]

>> It might be useful to visit log files previously saved from shell buffers,
>> like compilation-mode adds such local-variable prop-line:
>>
>>   -*- mode: compilation -*-
>
> I suppose the difference is compilation-mode does useful things when a
> compilation has finished, whereas shell-mode and similar would be more
> or less entirely for interaction.

It makes sense to visit a previously saved shell buffer only to
see highlighted prompts and command lines (that shell-mode
currently is unable to do).

> I've had file buffers in compilation-mode for stepping error lines in
> the way you say.  The only thing I've been tricked by is accidentally
> "g" recompile which replaces the file text -- in a sensible way, but for
> me usually not what I meant to do :-).

Maybe "g" should check if the compilation buffer is visiting a file,
and not to recompile in this case.