{base,dir}name // semantics

[Eric Blake]

POSIX allows implementations to define the behavior of 'basename //' and
'dirname //'.  Currently, both operations in coreutils output a single /, but
this definition is worthless on platforms (like cygwin) where // is distinct
from /.  The intent, according to POSIX, is that 'cd $(dirname "string")
&& stat $(basename "string")' access the same file as 'stat "string"'
would do.

I can look at preparing a patch to make both utilities output //,  which
would satisfy the intent of POSIX.  First, I have one question - should
this patch be made globally, or should it be limited to only systems
that have a distinct //, leaving other platforms to continue having just
a single slash returned?  I would argue that cross-platform consistency
is more important than reducing the output where // has no special
semantics, so the change should probably be made for all platforms.

--
Eric Blake