Remove random sleeping on commit

We're now holding the lock for commit, so this can not happen.

Signed-off-by: Michal Čihař <michal@cihar.com>
Hold repository lock only for repository operations

The other things do not have to be locked, we just need to protect the
repository.

Signed-off-by: Michal Čihař <michal@cihar.com>
Increase repository lock timeout

Signed-off-by: Michal Čihař <michal@cihar.com>