I have an interesting problem, when I try to build vtk for Python 3.8:

     # /usr/bin/dnf builddep --installroot /var/lib/mock/900764-fedora-rawhide-x86_64-1556745192.100416/root/ --releasever 31 --setopt=deltarpm=False --disableplugin=local --disableplugin=spacewalk --disableplugin=local --disableplugin=spacewalk /var/lib/mock/900764-fedora-rawhide-x86_64-1556745192.100416/root//builddir/build/SRPMS/vtk-8.2.0-4.fc31.src.rpm
    Error: 
     Problem 1: cannot install the best candidate for the job
      - nothing provides libmpi.so.12()(64bit) needed by python3-mpi4py-mpich-3.0.1-3.fc31.x86_64
     Problem 2: cannot install the best candidate for the job
      - nothing provides libmpi.so.40()(64bit) needed by python3-mpi4py-openmpi-3.0.1-3.fc31.x86_64


Indeed, I have rebuilt mpi4py for Python 3.8 and it requires:

    $ dnf repoquery --repo=python3.8 --requires python3-mpi4py-openmpi
    libc.so.6(GLIBC_2.14)(64bit)
    libdl.so.2()(64bit)
    libdl.so.2(GLIBC_2.2.5)(64bit)
    libmpi.so.40()(64bit)
    libpthread.so.0()(64bit)
    libpython3.8m.so.1.0()(64bit)
    mpi4py-common = 3.0.1-3.fc31
    python(abi) = 3.8
    python3-openmpi(x86-64)
    rtld(GNU_HASH)

    $ dnf repoquery --repo=python3.8 --requires python3-mpi4py-mpich
    libc.so.6(GLIBC_2.14)(64bit)
    libdl.so.2()(64bit)
    libdl.so.2(GLIBC_2.2.5)(64bit)
    libmpi.so.12()(64bit)
    libpthread.so.0()(64bit)
    libpython3.8m.so.1.0()(64bit)
    mpi4py-common = 3.0.1-3.fc31
    python(abi) = 3.8
    python3-mpich(x86-64)
    rtld(GNU_HASH)


However, in rawhide, it requires:

    $ dnf repoquery --repo=rawhide --requires python3-mpi4py-openmpi
    Nepodařilo se načíst plugin: py3query
    Poslední kontrola metadat: před 0:14:02, Čt 2. května 2019, 00:48:02 CEST.
    libc.so.6(GLIBC_2.14)(64bit)
    libdl.so.2()(64bit)
    libdl.so.2(GLIBC_2.2.5)(64bit)
    libmpi.so.40()(64bit)(openmpi-x86_64)
    libpthread.so.0()(64bit)
    libpython3.7m.so.1.0()(64bit)
    mpi4py-common = 3.0.1-2.fc31
    python(abi) = 3.7
    python3-openmpi(x86-64)
    rtld(GNU_HASH)

    $ dnf repoquery --repo=rawhide --requires python3-mpi4py-mpich
    Nepodařilo se načíst plugin: py3query
    Poslední kontrola metadat: před 0:14:09, Čt 2. května 2019, 00:48:02 CEST.
    libc.so.6(GLIBC_2.14)(64bit)
    libdl.so.2()(64bit)
    libdl.so.2(GLIBC_2.2.5)(64bit)
    libmpi.so.12()(64bit)(mpich-x86_64)
    libpthread.so.0()(64bit)
    libpython3.7m.so.1.0()(64bit)
    mpi4py-common = 3.0.1-2.fc31
    python(abi) = 3.7
    python3-mpich(x86-64)
    rtld(GNU_HASH)


Notice the difference between:

    libmpi.so.40()(64bit) and libmpi.so.40()(64bit)(openmpi-x86_64)
    libmpi.so.12()(64bit) and libmpi.so.12()(64bit)(mpich-x86_64)


Is this something that's relevant to python 3.8, or is something else broken entirely?

I've tried to rebuild mpi4py in rawhide Koji, to see what it would require, but it FTBFS on 3 architectures:

https://koji.fedoraproject.org/koji/taskinfo?taskID=34566237

It however includes the suffix on the not-failed ones:

    libmpi.so.12()(64bit)(mpich-s390x)

Relevant Copr builds:

https://copr.fedorainfracloud.org/coprs/g/python/python3.8/build/891230/ mpi4py
https://copr.fedorainfracloud.org/coprs/g/python/python3.8/build/900764/ vtk