bug#14030: 24.3; expand-file-name expands remote file name on Windows incorrectly

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: vidagabor@gmail.com,  14030@debbugs.gnu.org
> Date: Mon, 25 Mar 2013 09:36:07 +0100
> 
> Well. I have reverted the change of `tramp-drop-volume-letter' to the
> definition as it has been before the change in #105625. Compiled
> tramp.el and tramp-sh.el on GNU/Linux. Copied the resulting tramp.elc
> and tramp-sh.elc into the Emacs 24.3 tree on MS Windows. The problem
> persists.

Revision 105625 cannot be the culprit, because it was done well before
Emacs 24.2 (which doesn't have the problem) was released.  It's got to
be something in the byte compiler.

> I have the impression, that there is a byte-compiler optimization, which
> throws away the call of `tramp-drop-volume-letter' in
> `tramp-sh-handle-expand-file-name'. As I have said earlier,
> (tramp-drop-volume-letter "c:/something") still works correctly.
> 
> How could I avoid this eager optimization?

How about making tramp-drop-volume-letter a simple function?