Bug#775364: debian-installer: Fails to install GNOME and Xfce at the same time using tasksel

[Ludovic Rousseau <rousseau@debian.org>]

Package: debian-installer
Version: debian-jessie-DI-b2-amd64-netinst.iso
Severity: normal

I used debian-jessie-DI-b2-amd64-netinst.iso
MD5 (debian-jessie-DI-b2-amd64-netinst.iso) = e4293f3b05d7d4288d590a211e471ad4

I wanted to install both GNOME and Xfce. But that fails with the error:
 Installation step failed
An installation step failed. You can try to run the failing item again
from the menu, or skip it and choose something else. The failing step
is: Select and install software


I tried again with the daily built image (for 14 January 2015) and the
problem is still present.

The /var/log/syslog file contains:
[...]
Jan 14 17:16:37 pkgsel: starting tasksel
Jan 14 17:21:58 in-target: Reading package lists...
Jan 14 17:21:58 in-target: 
Jan 14 17:21:58 in-target: Building dependency tree...
Jan 14 17:21:58 in-target: 
Jan 14 17:21:58 in-target: Reading state information...
Jan 14 17:21:58 in-target: Some packages could not be installed. This may mean that you have
Jan 14 17:21:58 in-target: requested an impossible situation or if you are using the unstable
Jan 14 17:21:58 in-target: distribution that some required packages have not yet been created
Jan 14 17:21:58 in-target: or been moved out of Incoming.
Jan 14 17:21:58 in-target: The following information may help to resolve the situation:
Jan 14 17:21:58 in-target: 
Jan 14 17:21:58 in-target: The following packages have unmet dependencies:
Jan 14 17:21:58 in-target:  task-gnome-desktop : Depends: gnome-core but it is not going to be installed
Jan 14 17:21:58 in-target:                       Recommends: gnome but it is not going to be installed
Jan 14 17:21:58 in-target: E
Jan 14 17:21:58 in-target: : 
Jan 14 17:21:58 in-target: Unable to correct problems, you have held broken packages.
Jan 14 17:21:58 in-target: 
Jan 14 17:21:59 in-target: tasksel: apt-get failed (100)


I can install Xfce if I unselect GNOME. I guess there is a conflict
between gnome-core and task-xfce-desktop

-- System Information:
Debian Release: 8.0
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_FR.utf8, LC_CTYPE=fr_FR.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)