gnome-core is preventing gnome from installing

Hi, I have sent the following to the developers mailing list but awaiting moderation after two days.

Currently on Trisquel 7`gnome` has broken dependency and could not be installed because of `gnome-core` package.
The problem is that gnome-core depends on firefox instead of abrowser or icecat.
I have written a package helper to solve this issue, but because it is the first time I am writing a package helper it might be incorrect. The control file in `meta-gnome3` package must be modified.

#!/bin/sh
#
# Copyright (C) 2014 Rubén Rodríguez <name at domain>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#

compile