bug#17218: 24.3; Dired does not insert subdirs when used with switch "--group-directories-first"

[Juri Linkov]

Version: 24.5

>>> I found out the problem in the function "dired-insert-old-subdirs"
>>> at line 1367 in dired.el.
>>
>> There is a similar problem in `dired-sort-R-check' and
>> `dired-build-subdir-alist'.
>>
>> [There probably should be a function that checks for a given switch,
>> and does not just use `string-match-p' in such a simple way.
>> (At least it should respect case etc.)]
>
> Below is the implementation of such a function:

Installed to trunk since this is not a regression.