bug#12339: Bug: rm -fr . doesn't dir depth first deletion yet it is documented to do so.

[Voelker, Bernhard]

Andreas Schwab wrote:
> [...] read the second paragraph:
>
>     If either of the files dot or dot-dot are specified as the basename
>     portion of an operand (that is, the final pathname component) or if
>     an operand resolves to the root directory, rm shall write a
>     diagnostic message to standard error and do nothing more with such
>     operands.

Coreutils has already implemented an exception for the root
directory: --no-preserve-root (whatever this would be useful
for except investigating what'd happen in a VM ...).

So it'd be possible to have another new switch to exceptionally
permit removing ".", although - again - I don't see much gain
over `rm -rf "$PWD"` or `find . -delete`.

-1 from me.

Moreover, I'd remove support for --[no-]preserve-root in rm:
preserving is mandatory by POSIX, and not preserving is senseless.

Have a nice day,
Berny