disallow implicit conversion of Field to boolean

5 jobs for NIFTy_4 in 12 minutes and 22 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Build Docker
passed build_docker_from_scratch #556960

00:07:06

 
  Test
passed test_python2_with_coverage #556961

00:04:23

79.0%
passed test_python3 #556962

00:04:21

 
  Release
passed pages #556963

00:00:53

 
  Deploy
passed pages:deploy

00:00:00