Arch Linux

First of all mariadb creates /var/lib/mysql in PKGBUILD now. But despite the array "options=('emptydirs')" in package_mariadb(), /var/lib/mysql ,for some reason, will not exists in the package:

https://www.archlinux.org/packages/extra/x86_64/mariadb/files/

[tom@localhost ~]$ ls -A packages/mariadb/trunk/pkg/mariadb
etc .INSTALL .MTREE .PKGINFO usr

I am not sure if it's a makepkg bug or we are missing something.

The second thing is, I see no reason /var/lib/mysql should be managed by the PKGBUILD anyway. If the directory is empty when the package is being removed, it get removed as well, while the "mysql" user stays:

[tom@localhost ~]$ journalctl -b -1 -u shadow
-- Logs begin at Sat 2015-06-20 06:47:52 HKT, end at Sun 2015-07-05 02:13:56 HKT. --
Jul 05 01:34:13 localhost systemd[1]: Starting Verify integrity of password and group files...
Jul 05 01:34:13 localhost pwck[251]: user 'mysql': directory '/var/lib/mysql' does not exist
Jul 05 01:34:13 localhost pwck[251]: pwck: no changes
Jul 05 01:34:13 localhost systemd[1]: shadow.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
Jul 05 01:34:13 localhost systemd[1]: Failed to start Verify integrity of password and group files.
Jul 05 01:34:13 localhost systemd[1]: shadow.service: Unit entered failed state.
Jul 05 01:34:13 localhost systemd[1]: shadow.service: Failed with result 'exit-code'.

You may argue something like: mostly the directory will not be empty, or, the user can delete the user manually, but why does it need to be managed by the PKGBUILD anyway while it's data directory? So I think it's better to revert to the .install way (just for the directory, not the user management thing).

Speaking of user management, you changed -g mysql to -g 89 in post_install() but you forgot to do that in post_upgrade().