Percona Server 5.7 can't be restarted after TokuDB has been installed with ps_tokudb_admin

This is because of when you are going to install percona-server-server-5.7 it will remove percona-server-tokudb-5.6 but not install new percona-server-tokudb-5.7 package :

root@percona-XPS-15:~# sudo apt-get install percona-server-server-5.7
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  percona-server-client-5.7 percona-server-common-5.7
The following packages will be REMOVED:
  percona-server-client-5.6 percona-server-server-5.6
  percona-server-tokudb-5.6
The following NEW packages will be installed:
  percona-server-client-5.7 percona-server-common-5.7
  percona-server-server-5.7

Process Will end up:

No directory, logging in with HOME=/
.151228 10:46:59 mysqld_safe mysqld_safe must be run as root for setting transparent huge pages!
.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................

Killing the process:
............../var/lib/dpkg/info/percona-server-server-5.7.postinst: line 87: 5963 Killed invoke-rc.d mysql start
dpkg: error processing package percona-server-server-5.7 (--configure):
 subprocess installed post-installation script returned error exit status 137
Processing triggers for ureadahead (0.100.0-16) ...
Errors were encountered while processing:
 percona-server-server-5.7

If you remove thp-setting=never from my.cnf still will not be able to start PS with TokuDB:

2015-12-28T06:57:08.671881Z 0 [ERROR] Can't open shared library '/usr/lib/mysql/plugin/tokudb_backup.so' (errno: 0 /usr/lib/mysql/plugin/tokudb_backup.so: cannot open shared ob
ject file: No such file or directory)
2015-12-28T06:57:08.671887Z 0 [Warning] Couldn't load plugin named 'tokudb_backup' with soname 'tokudb_backup.so'.
2015-12-28T06:57:08.671901Z 0 [ERROR] Can't open shared library '/usr/lib/mysql/plugin/ha_tokudb.so' (errno: 0 /usr/lib/mysql/plugin/ha_tokudb.so: cannot open shared object fil
e: No such file or directory)
2015-12-28T06:57:08.671905Z 0 [Warning] Couldn't load plugin named 'TokuDB' with soname 'ha_tokudb.so'.
2015-12-28T06:57:08.671914Z 0 [ERROR] Can't open shared library '/usr/lib/mysql/plugin/ha_tokudb.so' (errno: 0 /usr/lib/mysql/plugin/ha_tokudb.so: cannot open shared object fil
e: No such file or directory)
2015-12-28T06:57:08.671917Z 0 [Warning] Couldn't load plugin named 'TokuDB_file_map' with soname 'ha_tokudb.so'.
2015-12-28T06:57:08.671926Z 0 [ERROR] Can't open shared library '/usr/lib/mysql/plugin/ha_tokudb.so' (errno: 0 /usr/lib/mysql/plugin/ha_tokudb.so: cannot open shared object fil
e: No such file or directory)
2015-12-28T06:57:08.671929Z 0 [Warning] Couldn't load plugin named 'TokuDB_fractal_tree_info' with soname 'ha_tokudb.so'.
2015-12-28T06:57:08.671938Z 0 [ERROR] Can't open shared library '/usr/lib/mysql/p...

This issue is happening because in 5.6 the mysqld_safe was run as root user. In 5.7 upstream runs it as mysql user.
Now since we need to run it as root user because of some tokudb pre-requisites I will change it so that it runs as root. If there will be complaints we will see how to proceed.

@rzayev-sehriyar
The thing here is that percona-server-server package doesn't depend on tokudb package. TokuDB package depends on the server package.
So if you did run "apt-get upgrade" or "apt-get dist-upgrade" or specifying "apt-get install percona-server-server-5.7 percona-server-tokudb-5.7" it would work.
I think it works the same between different 5.6 versions so not sure currently what can be done with that.

PR: https://github.com/percona/percona-server/pull/300

Reverted the previous fix as it wasn't complete and it wasn't a good idea.
The new fix was done here: https://github.com/percona/percona-server/pull/342

Basically mysqld_safe is run as mysql user but we have added a check into init scripts which run with root permissions before mysqld_safe to check for THP setting and set it if needed.
This is much cleaner solution.

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-3346