Like $GIT_CONFIG, $GIT_CONFIG_PARAMETERS needs to be suppressed by
"git push" and its cousins when running local transport helpers to
imitate remote transport well.
Noticed-by: Jeff King <peff@peff.net> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>