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

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: Vida Gábor <vidagabor@gmail.com>,
>   14030@debbugs.gnu.org
> Date: Sat, 23 Mar 2013 13:13:37 +0100
> 
> This is competely strange. In `tramp-sh-handle-expand-file-name', there
> is the following code at the very end:
> 
>       (let ((directory-sep-char ?/)
>           (default-directory (tramp-compat-temporary-file-directory)))
>       (tramp-make-tramp-file-name
>        method user host
>        (tramp-drop-volume-letter
>         (tramp-run-real-handler
>          'expand-file-name (list localname)))
>        hop)))))
> 
> In Emacs 24.3, `tramp-drop-volume-letter' is not executed:
> 
> | | | | 5 -> tramp-run-real-handler: operation=expand-file-name 
> args=("/root/")
> | | | | 5 <- tramp-run-real-handler: "c:/root/"
> | | | | 5 -> tramp-make-tramp-file-name: method="plink" user=nil host="ford" 
> localname="c:/root/" hop=nil
> | | | | 5 <- tramp-make-tramp-file-name: "/plink:ford:c:/root/"
> 
> When I use Emacs 24.3.50, the latest snapshot, that function is
> executed:
> 
> | | | | 5 -> (tramp-run-real-handler expand-file-name ("/root/"))
> | | | | 5 <- tramp-run-real-handler: "c:/root/"
> | | | | 5 -> (tramp-drop-volume-letter "c:/root/")
> | | | | 5 <- tramp-drop-volume-letter: "/root/"
> | | | | 5 -> (tramp-make-tramp-file-name "plink" nil "ford" "/root/" nil)
> | | | | 5 <- tramp-make-tramp-file-name: "/plink:ford:/root/"
> 
> I have no idea, what prevents `tramp-drop-volume-letter' to be called.

Since tramp-drop-volume-letter is not a function, it's a defalias, so
maybe it somehow doesn't get registered in the trace?

Or maybe it somehow takes the 'identity route?