Bug#691498: gdm3/experimental: document that ~/.xsession-errors is no longer used

[Simon McVittie]

Package: gdm3
Version: 3.6.1-1
Severity: wishlist

>From NEWS:

> =============
> Version 3.5.2
> =============
> 
> ...
> 
> - save log to $XDG_CACHE_HOME/gdm/session.log instead of ~/.xsession-errors

This is a good thing in the long term - I approve of reducing crap in $HOME -
but it's going to confuse people who're debugging GNOME 3.6 or other X apps,
particularly those that are "part of the session" and so can't easily be
restarted with stderr visible (gnome-shell, gnome-session,
gnome-settings-daemon etc.). I've been tricked by it already.

I'm not sure what the best solution is, though. Options include:

* say something in NEWS.Debian

* on session start, if ~/.xsession-errors exists and is a regular file,
  replace it with text like "Session started by GDM,
  see ~/.cache/gdm/session.log" (I think this is probably the one that
  will "interoperate" best with startx and other display managers, since
  they'll overwrite .xsession-errors with their own session logs on login, as
  expected - so it'll always contain either a non-GDM session log, or a
  pointer to the GDM log)

* on session start, if ~/.xsession-errors exists and is a regular file,
  replace it with a symlink to ~/.cache/gdm/session.log (this interops
  poorly with other display managers, but might be better for bug-reporting
  tools that know about ~/.xsession-errors)

* log to ~/.xsession-errors if it exists, or ~/.cache/gdm/session.log in new
  installations

* agree on a session log location in $XDG_CACHE_HOME with the maintainers
  of x11-common, and patch both x11-common and gdm3 to be consistent

-- System Information:
Debian Release: wheezy/sid
  APT prefers testing-proposed-updates
  APT policy: (500, 'testing-proposed-updates'), (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.2.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages gdm3 depends on:
ii  accountsservice                             0.6.24-1
ii  adduser                                     3.113+nmu3
ii  dconf-gsettings-backend                     0.14.0-1
ii  dconf-tools                                 0.14.0-1
ii  debconf [debconf-2.0]                       1.5.46
ii  dpkg                                        1.16.9
ii  gir1.2-glib-2.0                             1.34.1.1-1
ii  gnome-session [x-session-manager]           3.6.0-1
ii  gnome-session-bin                           3.6.0-1
ii  gnome-session-fallback [x-session-manager]  3.6.0-1
ii  gnome-settings-daemon                       3.6.1-1
ii  gnome-terminal [x-terminal-emulator]        3.4.1.1-2
ii  gsettings-desktop-schemas                   3.6.0-1
ii  libaccountsservice0                         0.6.24-1
ii  libatk1.0-0                                 2.6.0-1
ii  libaudit0                                   1:1.7.18-1.1
ii  libc6                                       2.13-35
ii  libcairo-gobject2                           1.12.2-2
ii  libcairo2                                   1.12.2-2
ii  libcanberra-gtk3-0                          0.28-5
ii  libcanberra0                                0.28-5
ii  libfontconfig1                              2.9.0-7
ii  libgdk-pixbuf2.0-0                          2.26.4-2
ii  libglib2.0-0                                2.34.1-1
ii  libglib2.0-bin                              2.34.1-1
ii  libgtk-3-0                                  3.6.1-1
ii  libpam-modules                              1.1.3-7.1
ii  libpam-runtime                              1.1.3-7.1
ii  libpam0g                                    1.1.3-7.1
ii  libpango1.0-0                               1.30.0-1
ii  librsvg2-common                             2.36.4-1
ii  libselinux1                                 2.1.9-5
ii  libupower-glib1                             0.9.17-1
ii  libwrap0                                    7.6.q-24
ii  libx11-6                                    2:1.5.0-1
ii  libxau6                                     1:1.0.7-1
ii  libxdmcp6                                   1:1.1.1-1
ii  libxrandr2                                  2:1.3.2-2
ii  lsb-base                                    4.1+Debian7
ii  metacity [x-window-manager]                 1:2.34.3-3
ii  mutter [x-window-manager]                   3.6.1-1
ii  openbox [x-window-manager]                  3.5.0-4
ii  policykit-1-gnome                           0.105-2
ii  upower                                      0.9.17-1
ii  x11-common                                  1:7.7+1
ii  x11-xserver-utils                           7.7~3
ii  xterm [x-terminal-emulator]                 278-2

Versions of packages gdm3 recommends:
ii  at-spi2-core               2.7.1-1
ii  desktop-base               7.0.3
ii  gnome-icon-theme           3.6.0-1
ii  gnome-icon-theme-symbolic  3.6.0-1
ii  x11-xkb-utils              7.7~1
ii  xserver-xephyr             2:1.12.4-1
ii  xserver-xorg               1:7.7+1
ii  zenity                     3.4.0-2

Versions of packages gdm3 suggests:
ii  gnome-orca            3.4.2-2
ii  gnome-shell           3.6.1-3
pn  gok                   <none>
ii  libpam-gnome-keyring  3.6.1-1

-- debconf information:
* shared/default-x-display-manager: gdm3
  gdm3/daemon_name: /usr/sbin/gdm3