bug#13033: 24.3.50; regression: read-file-name-internal handles "~" wrong

["Drew Adams" <drew.adams@oracle.com>]

This is on Windows.  I have Cygwin installed, but that should not
affect how Emacs interprets `~'.
 
My `user-login-name' is "dradams".  My `user-full-name' is "".
 
In this Emacs version,
(read-file-name-internal "~" 'file-exists-p nil) returns "~/dradams/".
 
That is wrong.  Not only is there no such directory as ~/dradams/".  But
my HOME environment variable is defined as "c:\\".
 
In 24.2 and in all previous Emacs versions (with the 2nd arg a dir, as needed),
(read-file-name-internal "~" 'file-exists-p nil) returns nil.
 
Please revert the code that causes this regression.

In GNU Emacs 24.3.50.1 (i386-mingw-nt5.1.2600)
 of 2012-11-19 on MS-W7-DANI
Bzr revision: 110950 monnier@iro.umontreal.ca-20121119182725-5p6w4wjimm7epggr
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -Ic:/emacs/libs/libXpm-3.5.10/include -Ic:/emacs/libs/libXpm-3.5.10/src
 -Ic:/emacs/libs/libpng-1.2.37-lib/include -Ic:/emacs/libs/zlib-1.2.5
 -Ic:/emacs/libs/giflib-4.1.4-1-lib/include
 -Ic:/emacs/libs/jpeg-6b-4-lib/include
 -Ic:/emacs/libs/tiff-3.8.2-1-lib/include
 -Ic:/emacs/libs/libxml2-2.7.8-w32-bin/include/libxml2
 -Ic:/emacs/libs/gnutls-3.0.9-w32-bin/include
 -Ic:/emacs/libs/libiconv-1.9.2-1-lib/include'