[debian-mysql] Fixing the jessie->stretch upgrade path

[Ondřej Surý]

Dear release team and fellow MySQL/MariaDB maintainers,

the situation in stretch in regards to clean upgrade path from jessie is
a little bit unfortunate. It works for most cases when something depends
on default-mysql-server and pulls it as a dependency. But in situations
where mysql-server was the top dependency, it simply uninstalls
mysql-server-5.5 without any replacement.

I understand the reasons why we are here, but the situation where user
needs to do:
apt-get update
# apt-get upgrade
apt-get install default-mysql-server
apt-get dist-upgrade

is very inconvenient for the users and I foresee this will cause a lot
of complaints, because it's quite common to run just "mysql-server" on
the server.

Therefore I am proposing a one time fix specifically targeted at
stretch. I would like to prepare 'mysql-transitional' package that will
create a couple of dummy/transitional packages structured like this:

mysql-server depends on default-mysql-server
mysql-client depends on default-mysql-client

The version would be 5.5.999+mariadb, so it is always higher than
version in jessie, but always lower than version in sid, as I don't want
force epoch on mysql-5.7.

This upload would have to go directly into stretch, so an approval of
release team is required.

Cheers,
-- 
Ondřej Surý <ondrej at sury.org>
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