Make opam behave correctly on a dumb terminal

opam.bash

#
# Make sure opam never colorizes
#
opam () {
    local direct_opam
    if hash /usr/local/bin/opam 2> /dev/null; then
        direct_opam=/usr/local/bin/opam
    elif hash /usr/bin/opam 2> /dev/null; then
        direct_opam=/usr/bin/opam
    elif hash /bin/opam 2> /dev/null; then
        direct_opam=/bin/opam
    else
        echo "Opam must be installed"
        exit 1
    fi
    
    local main_target="$1"
    shift
    $direct_opam $main_target --color=never $*
}