GREP_OPTIONS and color

[Stefan]

Old GNU greps like the version 2.4.2 distributed with Mac OS X don't like
the --color=always option.  Here's what I get in the *Grep* buffer:

   cd /Users/monnier/src/emacs/work/lisp/gnus/  # -*-grep-*-
   Entering directory `/Users/monnier/src/emacs/work/lisp/gnus/'
   grep -nH mm-decode-coding-string  *.el
   grep: unrecognized option `--color=always'
   Usage: grep [OPTION]... PATTERN [FILE]...
   Try `grep --help' for more information.
   
   Grep exited abnormally with code 2 at Mon Sep  6 22:01:14


-- Stefan