Bug#590961: libao4: Please raise suggestions to depencies, breaks other software otherwise

[Alexander Kurtz]

Package: libao4
Version: 1.0.0-4
Severity: serious
Justification: Breaks other software

Hi,

since version 2.30 brasero[1] (a graphical burning program) explicitly
checks the versions of the third-party tools it is using[2]; among these
is cdrdao[3] (Disk-At-Once recorder). Normally this looks like this:

 $ cdrdao version | sed 's/^/STDIN:/g'
 Cdrdao version 1.2.3 - (C) Andreas Mueller <andreas at daneb.de>

 (As you can see everything goes to stderr)

Now if libaudio2[4] is not installed it looks like this:

 $ cdrdao version | sed 's/^/STDIN:/g'
 ERROR: Failed to load plugin /usr/lib/ao/plugins-4/libnas.so => dlopen() failed
 Cdrdao version 1.2.3 - (C) Andreas Mueller <andreas at daneb.de>

This is because /usr/lib/ao/plugins-4/libnas.so links against
libaudio.so.2 which is provided by libaudio2. As a consequence brasero
can't parse the cdrdao version string anymore (see [5]) and thus fails
to recognize it correctly which results in audio disc creation being
disabled.

Now most users won't see this error because some other package pulled in
libaudio2, but if not, unrelated things like brasero will break.

This problem is not limited to libaudio2 but also affects the other
suggestions. If I install cdrdao in a fresh chroot set up by debootstrap
I get this:

 $ cdrdao version | sed 's/^/STDIN:/g'
 ERROR: Failed to load plugin /usr/lib/ao/plugins-4/libalsa.so => dlopen() failed
 ERROR: Failed to load plugin /usr/lib/ao/plugins-4/libnas.so => dlopen() failed
 ERROR: Failed to load plugin /usr/lib/ao/plugins-4/libpulse.so => dlopen() failed
 ERROR: Failed to load plugin /usr/lib/ao/plugins-4/libesd.so => dlopen() failed
 Cdrdao version 1.2.3 - (C) Andreas Mueller <andreas at daneb.de>

Note that not only software packaged in Debian might parse such version
strings but also local programs, scripts, etc. We should therefore
prevent this error messages from screwing up things by preventing them
from being printed at all. And that can only happen by changing libao4's
suggestions[6] to depencies.

Best Regards

Alexander Kurtz

[1] http://packages.debian.org/sid/brasero
[2] http://git.gnome.org/browse/brasero/commit/?id=62bda5dab82ddba07b0d1af3af333860a97d39c3
[3] http://packages.debian.org/sid/cdrdao
[4] http://packages.debian.org/sid/libaudio2
[5] http://git.gnome.org/browse/brasero/diff/plugins/cdrdao/burn-cdrdao.c?id=62bda5dab82ddba07b0d1af3af333860a97d39c3
[6] http://packages.debian.org/sid/libao4
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