Bogus tempfile names in beta18

[Vinnie Shelton <shelton@xxxxxxxxxxxxxxxx>]

This bug has been around for awhile.  Someone (Peter?) sent a fix, but I 
foolishly discarded it, assuming that fix would be incorporated in beta18.  
Basically, the bug is that filenames for =() substitution are not unique.  Eg:

: zsh-2.6-beta18/SunOS Wed 22 11:02; Src/zsh -f
spacely% echo $ZSH_VERSION
2.6-beta18
spacely% uname -a 
SunOS spacely 4.1.3_U1 2 sun4m
spacely% echo =(ls /tmp) =(ls)
/tmp/zsha19197 /tmp/zshb19197

If one were to diff those (supposedly) two files, they would apparently be the 
same, even though they should be different.

--vin