update repo recreation details

Update based on https://github.com/gitlabhq/gitlabhq/blob/master/doc/install/installation.md#configure-it and https://github.com/gitlabhq/gitlabhq/blob/master/doc/update/6.0-to-7.2.md#6-install-libs-migrations-etc.
Why exactly is the last line needed? It safer yes - but is it needed?