Consider the following interaction:
| # apt install docbook-xsl
| # grep delegateURI.*xsl /etc/xml/catalog
| <delegateURI uriStartString="http://docbook.sourceforge.net/release/xsl/" catalog="file:///etc/xml/docbook-xsl.xml"/>
| # update-xmlcatalog --del --type uri --id "http://docbook.sourceforge.net/release/xsl/" --root
| # grep delegateURI.*xsl /etc/xml/catalog
| # apt reinstall docbook-xsl
| # grep delegateURI.*xsl /etc/xml/catalog
| <delegateURI uriStartString="http://docbook.sourceforge.net/release/xsl/" catalog="file:///etc/xml/docbook-xsl.xml"/>
| #
We can see that apt reinstall docbook-xsl changed the contents of
/etc/xml/catalog. This also happens during package upgrades. The prerm
script removes docbook-xsl from the root catalog and the postinst script
adds it back. Thus, removal by a user is not preserved. This is a
violation of Debian policy section 10.7.3, which says "local changes
must be preserved during a package upgrade".
We had a very similar issue with the sgml super catalog. Read up on
#88010 and #477751. Fixing that one was very painful. It required a lot
of uploads and we ran into bugs with dpkg triggers. I guess that this
bug is similarly painful. On the bright side, fixing this has the
potential to remove a lot of maintainer scripts and move us towards more
declarative packaging.
Unfortunately, it really is a violation of the policy and we should
either fix this bug or policy. I'm unsure how to proceed here, so I just
report it. Good luck.
Helmut