Parallelise GetEntry only if number of independent branches is greater than 1
Parallelise GetEntry only if number of independent branches is greater than 1

this avoids the overhead of launching a single work item in the pool of worker
threads.

karies/root,karies/root,karies/root,root-mirror/root,karies/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,karies/root,root-mirror/root,root-mirror/root,olifre/root,karies/root,olifre/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,olifre/root,karies/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,karies/root,karies/root,karies/root,olifre/root