Windows only bug: file-truename does not return consitent value for non-existant files

[Andrew Maguire]

This bug report will be sent to the Free Software Foundation,
 not to your local site managers!!
Please write in English, because the Emacs maintainers do not have
translators to read other languages for them.

In GNU Emacs 20.3.7.1 (sparc-sun-solaris2.5.1, X toolkit)
 of Fri Apr 23 1999 on uranium
configured using `configure  --x-includes=/usr/openwin/include 
--x-libraries=/usr/openwin/lib --libexecdir=/usr/local/lib 
--infodir=/usr/local/share/info'

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

On Windows I am using GNU Emacs 20.7.2 (i386-*-nt4.0.1381)

(file-truename "C:/temp/a_file")
returns "C:/temp/a_file" if the file does not exist
and "c:/temp/a_file" if it does.

This causes confusion if you do a find-file on C:/temp/a_file
edit it and save it. Then do a find-file on c:/temp/a_file.
You will get two different edits on the same file.

I guess the solution is to either:
downcase the drive letter so that if the file is created
then a subsequent w32-long-file-name call will return the same
or
to handle drive letters somewhere in the C code 

Recent input:
C-x C-s up C-e C-left C-left C-left C-left C-left C-left 
C-left C-left C-left left left C-k C-x C-s C-x k return 
C-x k return right right C-x k return C-x C-b C-x C-f 
up down C-e c s h r c . tab tab return next next next 
next next next next next next next next next next next 
next next next next next next next next next prior 
prior prior next next next down-mouse-1 mouse-1 C-h 
f f i l e - t r u e tab return down-mouse-2 mouse-2 
next next next next next next menu-bar help-menu r
eport-emacs-bug

Recent messages:
Getting PWD...done
Retrieving cshrc.setup...
Retrieving cshrc.setup...done
Listing cshrc.setup/...
Listing cshrc.setup/...done
Listing /andrewma@nitrogen:/usr/locshare/...
Listing /andrewma@nitrogen:/usr/locshare/...done
Type C-x 4 b RET to restore the other window.  M-C-v to scroll the help.
Loading emacsbug...
Loading emacsbug...done