Fix to 5c72c8f2ddecd8efae63c7ed1897791dbec0da26.
Fix to 5c72c8f2ddecd8efae63c7ed1897791dbec0da26.

The bug fix made in 5c72c8f2ddecd8efae63c7ed1897791dbec0da26
assumed that there were spawned walkers to annihilate.  This isn't
always true so needs to be tested for.

hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,ruthfranklin/hande