Fix possible ConcurrentModificationException when copying the system properties: use clone() instead which is synchronized
Fix interrupted threads when updating the agent.
Executors are simply shut down  but we let the current processing run to finish cleanly.
When controlled by the agent, this should not be a problem, as the agent is started at the very end of the process.
Avoid refreshes of fragments.
Add some information in the log about why a given bundle is selected for refresh.