mock: avoid the %pre scriptlet if possible

The script for generating the %pre scriptlet is non-existing on new
distributions (like Mageia now, but Fedora will drop that sooner or
later, too).  The build of Mock on Mageia previously relied on
sysusers.generate-pre.sh, and failed.

The sysusers feature is an RPM built-in anyway (on modern systems), so
there's no reason to duplicate the logic in %pre.  Generate the %pre
scriptlet only for older distributions.

Complements: #1367
Relates: #289
Relates: fedora-copr/copr#2789

mock/mock.spec

@@ -1,6 +1,22 @@
 %bcond_with lint
 %bcond_without tests
 
+# In modern distributions with RPM v4.19+ (e.g., Fedora 39+), the %%pre
+# scriptlet for creating users/groups is no longer necessary due to the built-in
+# sysusers feature.  To enable it, we simply include the `mock.conf` file in the
+# package payload so that RPM knows what actions to take.  For older
+# distributions, however, the %%sysusers_requires_compat macro is typically
+# used.  This macro isn't ideal for Mock's packaging style (tito) because it
+# requires mock.conf to be an additional SourceN file rather than within
+# `Source0` tarball.  Instead of using that macro, we manually generate the
+# scriptlet content for older distributions using the `sysusers.generate-pre.sh`
+# script (which is the `%%sysusers_requires_compat` "internal").
+%if 0%{?rhel} && 0%{?rhel} <= 9
+%bcond_without sysusers_compat
+%else
+%bcond_with sysusers_compat
+%endif
+
 %global __python %{__python3}
 %global python_sitelib %{python3_sitelib}
 
@@ -171,8 +187,9 @@ done
 
 ./precompile-bash-completion "mock.complete"
 
-# this is what %%sysusers_create_compat will expand to
-%{_rpmconfigdir}/sysusers.generate-pre.sh mock.conf > sysusers_script
+%if %{with sysusers_compat}
+%{_rpmconfigdir}/sysusers.generate-pre.sh mock.conf > sysusers_script || :
+%endif
 
 argparse-manpage --pyfile ./py/mock-hermetic-repo.py --function _argparser > mock-hermetic-repo.1
 
@@ -230,7 +247,9 @@ sed -i 's/^_MOCK_NVR = None$/_MOCK_NVR = "%name-%version-%release"/' \
     %{buildroot}%{_libexecdir}/mock/mock
 
 
+%if %{with sysusers_compat}
 %pre filesystem -f sysusers_script
+%endif
 
 
 %check

releng/release-notes-next/sysusers-on-mageia.bugfix

@@ -0,0 +1,2 @@
+The %pre scriptlet is not generated for modern distributions like Fedora 39+ or
+Mageia (group/user additions are handled by an RPM built-in feature).