POSIX allows one or more trailing slashes for directories.
From POSIX.1-2008, section 3.271 (Base Definitions / Pathname):
> A pathname can optionally contain one or more trailing <slash>
> characters. Multiple successive <slash> characters are considered to
> be the same as one <slash>, except for the case of exactly two
> leading <slash> characters.
On Windows, the extra trailing slashes are ignored for directories too.