Bug#974181: python3-sasview: tests fail with h5py 3.1

[Drew Parsons]

Package: sasview
Followup-For: Bug #974181
Control: forwarded -1 https://github.com/SasView/sasview/issues/1710

Going through the data access step by step by hand following the steps
in read_children() from sas/sascalc/dataloader/readers/cansas_reader_HDF5.py,
the .h5 files seem to be opening under h5py 3.1 well enough with their
contents accessible.

There must be something gone wrong in the fine print in what sasview
expects to get out of the .h5 files, or in how it expects h5py to
present the data.  Possibly something went wrong in the Debian
submodule installation of h5py (making both serial and mpi builds
available), though h5py passes other tests successfully (and as I
mentioned, the sasview steps using h5py to access the data run
successfully when run by hand)