Bug#904020: libpetsc-real3.9-dev: dependency on libopenmpi-dev not strict enough

[Drew Parsons]

On Thu, 2018-07-19 at 10:18 +0800, Drew Parsons wrote:
> 
> OpenMPI was libopenmpi-dev 3.1.0-7 in the failing deal.ii tests, and 
> libopenmpi-dev 3.1.1.real-3 in the successful tests. Either way
> that's
> still openmpi 3.1, so is supposed to be compatible.  
> 
> So looks like you're right, there may be a PETSc bug when it tests
> for
> mpi compatibility. openmpi 3.1.0 and 3.1.1. are both supposed to be
> fine, they should not be triggering the incompatibility warning.

The actual test (in the subminor version) is 
  (OMPI_RELEASE_VERSION < PETSC_HAVE_OMPI_RELEASE_VERSION)
which means you can't use an older subminor release, which is a
reasonable constraint that we can add to the petsc dependencies (you
can go forwards in subminor version but not backwards).

What it means is that PETSc was built against openmpi 3.1.1.  But you
were using openmpi 3.1.0 in the tests. It is related to the openmpi
transition, which has been all over the shop lately.  openmpi 3.1.1 is
still not in testing.

Drew