Bug#660607: liblapack3: postinst fails on upgrade ("error: alternative liblapack.so.3gf can't be slave of liblapack.so.3")

[Jonathan Nieder]

Package: liblapack3
Version: 3.4.0-1~exp2
Severity: serious
Justification: broken upgrade

Hi,

Just got a chance to try the upgraded liblapack3.  Alas, the behavior
matches the fears described here [1]:

> The Conflicts also seems insufficient, since it doesn't force other
> packages such as libatlas3gf-base for which liblapack.so.3gf is still
> the master link to be upgraded.

More precisely, I get

| Setting up liblapack3 (3.4.0-1~exp2) ...
| update-alternatives: warning: alternative /usr/lib/lapack/liblapack.so.3gf (part of link group liblapack.so.3gf) doesn't exist. Removing from list of alternatives.
| update-alternatives: error: alternative liblapack.so.3gf can't be slave of liblapack.so.3: it is a master alternative.
| dpkg: error processing liblapack3 (--install):

And:

| # ls -l /etc/alternatives/liblapack.so.3gf 
| lrwxrwxrwx 1 root root 42 Feb 19 11:11 /etc/alternatives/liblapack.so.3gf -> /usr/lib/atlas-base/atlas/liblapack.so.3gf

Proposed strategy for fixing it:

>                                  Maybe a versioned Breaks against all
> packages in squeeze providing liblapack.so.3gf would help, so the
> upgrade path would be:
>
>	1. Unpack new versions of libraries providing liblapack.so.3gf
>	   en masse.  Preinst removes the old liblapack.so.3gf alternative.
>
>	2. Configure new versions of libraries providing
>	   liblapack.so.3gf.  Postinst adds the
>	   liblapack.so.3/liblapack.so.3gf link group.

Hope that helps,
Jonathan

[1] http://bugs.debian.org/656039