can't set a variable with a dash in its name!!

[Raphael Marmier]

On a freshly installed 4.8, while trying to install the mail/imp3 port, 
I realised that it was impossible to define the following variable, 
either in tcsh or sh:

re# setenv WITH_COURIER-IMAP
setenv: Syntax Error.
re# setenv WITH_COURIERIMAP
re#

re# sh
# export WITH_COURIER-IMAP
export: WITH_COURIER-IMAP: bad variable name
# export WITH_COURIERIMAP
#

I just tried on 4.6.2 and it works, as well as MacOSX.

The only customisation this system has received is CPUTYPE=p4 in 
make.conf, and rebuilt kernel and world after this. Everything has been 
normal since then.

idea anyone?

Raphael