[PATCH] improve event sequence serialization

[PATCH] improve event sequence serialization

We delay the execution of events if there is already an event running for
the same device, a parent or a child device. "add" events with a reference
to a physical device will also wait for the physical device to finish.

Here we fix the devpath comparison logic to return "busy" only if a complete
device names is matching. /block/sdaa will not longer block a /block/sda event.