Upstream database update not in a single step

["Jan-Pascal van Best" <janpascal@vanbest.org>]

Dear mentors,

I'm updating the spotweb package currently in Wheezy to a more recent
version. The packaging is in git on Alioth
(http://anonscm.debian.org/gitweb/?p=users/janpascal-guest/spotweb.git).
Package works fine in unstable, I think I've also tackled the other issues
with the package (removing an embedded library and replacing it with a
reference to the proper Debian package).

My problem is that upstream does not provide a single-step database
upgrade from the version in Wheezy to the current version. Normally
database upgrades are performed by running a PHP script (upgrade-db.php)
which uses a number of other PHP script. When upgrading to the most recent
release, the upstream upgrade script gives an error message and suggests
to download an intermediate version and run the upgrade-db script from
that version. Trouble is that said script needs the entire intermediate
release of Spotweb, so I can't just include the intermediate upgrade
script and call that from postinst.sh.

Any ideas on how to proceed?

Thanks for any suggestions!

Jan-Pascal