Bug#621720: is this an apt bug?

[David Kalnischkies <kalnischkies+debian@gmail.com>]

On Wed, Apr 27, 2011 at 20:20, Faheem Mitha <faheem@email.unc.edu> wrote:
> What is the broken or group here (and how is it broken?), and what is the
> other or group member? I assume these are both versions of the apache 2
> packages? And which invocation does this refer to, the

You request the remove of apache2.2-common which is a dependency of
apache2-mpm-worker which is an or'd dependency of apache2.
APT notices that apache2-mpm-worker is going to be removed and so
it tries to install the next or-member in this case apache2-mpm-prefork.
Fine so far, but unfortunately is apache2.2-common a dependency of
apache2-mpm-prefork so APT in squeeze marks it for installation: FAIL.
(that apache2.2-common is a dependency of apache2 can be ignored)
The option i mentioned above will prevent APT from trying other or-group
members so apache2 will need to be removed, too.

APT in unstable will notice that the remove of apache2.2-common was
requested, so it will not install it slowly telling the "news" all packages
which were marked for install before but are uninstallable as
apache2.2-common is in the tree and marked for removal.
This can work out as it does in the case here (on your and my system)
but fails for others (see merge) as APT doesn't know any more if the
package was installed only to move forward in a dead end or if it needs
to be installed because of a request (or both, which could happen, too).
The fix is as said to pass the mentioned "news" down the tree so every-
thing which would have been installed if the dead end would be a proper
street can be removed from the list of packages to install again instantly.


Best regards

David Kalnischkies