[perl #127772] mkdir($file) succeeds if $file exists and is a regular file

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# New Ticket Created by  Rob Hoelz 
# Please include the string:  [perl #127772]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=127772 >


To reproduce:

    $ touch /tmp/my-fake-directory
    $ perl6 -e 'say ?mkdir("/tmp/my-fake-directory")'
    True

I understand that we want to succeed in the common case that that directory 
already exists, but I'm wondering if that's the correct behavior and whether we 
should leave handling that case up to the user.