try to improve serialization test

4 jobs for misc_fixes in 57 seconds (queued for 36 seconds)
Status Job ID Name Coverage
  Test
canceled #165865
test_min

00:00:57

canceled #165866
test_mpi

00:00:52

canceled #165867
test_mpi_fftw

00:00:49

canceled #165868
test_mpi_fftw_hdf5

00:00:46