By not getting the currently selected row at arbitrary times.
This introduces a slight behavior change for an improbable edge case,
which could be viewed as an improvement:
If there are multiple filters active, and the first, higher priority one
could finished much faster than the second, lower priority one, the
following sequence

Wait for results from first filter
Press return
Move up or down
Second filter finishes/cancels

without this patch did not select the item where you pressed return, but
the item that was selected when the second filter finished.

Change-Id: Iba2c72e2494824de961782ba3fe0bb1041072614
Reviewed-by: David Schulz <david.schulz@qt.io>