Use a full blown lock file instead of a random file serially accessed
and containing unreliable pid information. Of course, pids can be
reused across fork()s, even if this is unlikely (but not impossible).
Use EntropyRepositoryBase.integrity_check() against installed packages
repository on startup (after 5 mins "grace" time) and notify possible
issues to frontends using the new signal called "signal_integrity_problem"