Bug#719266: apache2_invoke enconf ignores dependencies disabled by admin

["Jean-Michel Vourgère" <jmv_deb@nirgal.com>]

Package: apache2
Version: 2.4.6-2

If sysop disabled a module, then a maintainer script enable a module that
depends on the first one, they are both enabled, ignoring admin choice.

Example (from a fresh wheezy install upgraded to jessie):

# a2enmod proxy
Enabling module proxy.
# a2dismod proxy
Module proxy disabled.
# a2query -m proxy
No module matches proxy (disabled by site administrator)

# APACHE2_MAINTSCRIPT_PACKAGE=testpkg
# DPKG_MAINTSCRIPT_NAME=postinst
# APACHE2_MAINTSCRIPT_NAME=postinst
# APACHE2_MAINTSCRIPT_METHOD=configure
# . /usr/share/apache2/apache2-maintscript-helper postint configure
# apache2_invoke enmod proxy_http
apache2_invoke: Enable module proxy_http

# a2query -m proxy
proxy (enabled by maintainer script)

# grep Depends /etc/apache2/mods-available/proxy_http.load 
# Depends: proxy


I expected apache2_invoke enmod proxy_http to fail since its dependency proxy
module has been explicitly disabled by sysop.