Add an Obsoletes tag with the python39- prefix

.. for smoother upgrade from RHEL8

Related: rhbz#1990421

python-rpm-macros.spec

@@ -1,6 +1,6 @@
 Name:           python-rpm-macros
 Version:        3.9
-Release:        50%{?dist}
+Release:        51%{?dist}
 Summary:        The common Python RPM macros
 URL:            https://src.fedoraproject.org/rpms/python-rpm-macros/
 
@@ -66,6 +66,15 @@ Requires:       python-srpm-macros = %{version}-%{release}
 # For %%py_setup and import_all_modules.py
 Requires:       python-rpm-macros = %{version}-%{release}
 
+# We obsolete the old python39-rpm-macros for a smoother upgrade from RHEL8.
+# Since python39-rpm-macros are built from the python39 component in RHEL 8,
+# they're fully versioned (currently `0:3.9.7`), with the patch version likely
+# to increase in the future. RPM sorts this number as higher than `3.9`, which
+# is the version we have in RHEL 9. Therefore we're obsoleting with an Epoch 1
+# so that all versions from RHEL 8 are obsoleted (but we keep the possibility
+# of increasing the epoch in RHEL 8 to stop this).
+Obsoletes:      python39-rpm-macros < 1:%{version}-%{release}
+
 %description -n python3-rpm-macros
 RPM macros for building Python 3 packages.
 
@@ -107,6 +116,10 @@ install -m 644 import_all_modules.py %{buildroot}%{_rpmconfigdir}/redhat/
 
 
 %changelog
+* Tue Feb 08 2022 Tomas Orsava <torsava@redhat.com> - 3.9-51
+- Add Obsoletes tags with the python39- prefix for smoother upgrade from RHEL8
+- Related: rhbz#1990421
+
 * Tue Feb 01 2022 Miro Hrončok <mhroncok@redhat.com> - 3.9-50
 - Explicitly opt-out from Python name-based provides and obsoletes generators