I don't see any white space, the generated file looks like e.g. this: 

  libvirt_use_virtio_for_bridges=true
  block_migration_flag=VIR_MIGRATE_UNDEFINE_SOURCE, VIR_MIGRATE_PEER2PEER,VIR_MIGRATE_NON_SHARED_INC,VIR_MIGRATE_LIVE
  compute_driver=libvirt.LibvirtDriver