improve checks when drawing from DiagonalOperator

7 jobs for NIFTy_4 in 10 minutes and 23 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build Docker
passed #550642
build_docker_from_scratch

00:06:45

 
  Test
passed #550645
test_python2_mpi

00:02:21

passed #550643
test_python2_scalar

00:02:15

65.0%
passed #550646
test_python3_mpi

00:02:49

passed #550644
test_python3_scalar

00:01:41

 
  Release
passed #550647
pages

00:00:48

 
  Deploy
passed pages:deploy

00:00:00