Not necessarily the easiest way to fix just this bug, but the root cause
was using the (at that point uninitialized) cfg variable, so it seemed
sensible to just get rid of it to avoid that kind of crap.
Prior to this change we schedule summaries on each state change, i.e.
scanning->idle and idle->scanning, which is unnecessary. Now we only do
it on index updates, plus the immediate one on going syncing->idle.
