man-db's cron warns about dangling symlink

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Hi,

Short story:

# apt-get install mpich-bin
# dpkg -P mpich-bin
# symlinks  /usr/share/man/man1/ | grep dangling
dangling: /usr/share/man/man1/clog2alog.1.gz -> /etc/alternatives/clog2alog.1.gz
dangling: /usr/share/man/man1/upshot.1.gz -> /etc/alternatives/upshot.1.gz
dangling: /usr/share/man/man1/clog_print.1.gz -> /etc/alternatives/clog_print.1.gz
dangling: /usr/share/man/man1/mpirun.1.gz -> /etc/alternatives/mpirun.1.gz
etc.

And the result is that when man-db gets run from cron, it sends the
following mail:
/etc/cron.daily/man-db:
mandb: warning: /usr/share/man/man1/clog2alog.1.gz is a dangling symlink
mandb: warning: /usr/share/man/man1/upshot.1.gz is a dangling symlink
mandb: warning: /usr/share/man/man1/clog_print.1.gz is a dangling symlink
mandb: warning: /usr/share/man/man1/mpirun.1.gz is a dangling symlink
etc.

The bug is that although the mpich-bin package uses
update-alternatives --install on postinst for all these files, it uses
update-alternatives --remove only on /usr/lib/mpich/bin/mpirun, leaving
a bunch of dangling symlinks...

The reason why I'm mailing debian-devel is that I've seen this behavior
quite often in the past, in various packages.  I hence guess there
should be some automatic way to check that a package correctly removes
the alternatives it provides.

Samuel