Trying to build with newer rpm version (in Fedora) results in:

error: line 601: Trigger fired by the same package is already defined in spec file: %triggerin -- samba-client

That's because we have two '%triggerun -- %{name}' with overlapping version intervals:

<spec snippet>
%triggerun -- %{name} < 1:1.5.0-22
# This package is allowed to autostart; however, the upgrade trigger
# in Fedora 16 final failed to actually do this.  Do it now as a
# one-off fix for bug #748841.
/bin/systemctl --no-reload enable %{name}.{service,socket,path} >/dev/null 2>&1 || :

%triggerun -- %{name} < 1:1.5-0.9
# Save the current service runlevel info
# User must manually run systemd-sysv-convert --apply cups
# to migrate them to systemd targets
%{_bindir}/systemd-sysv-convert --save %{name} >/dev/null 2>&1 || :

# This package is allowed to autostart:
/bin/systemctl --no-reload enable %{name}.{service,socket,path} >/dev/null 2>&1 || :

# Run these because the SysV package being removed won't do them
/sbin/chkconfig --del cups >/dev/null 2>&1 || :
/bin/systemctl try-restart %{name}.service >/dev/null 2>&1 || :
</spec snippet>

The story behind these two triggers is bug #748841. Tim first fixed [1] the '< 1:1.5-0.9' trigger and then added [2] another trigger for already updated packages.

From bug #1247140, comment #1:
"Previously rpm didn't refuse to build packages with overlapping version intervals but rpm always set off only one trigger. So probably triggers in your package didn't work as you expected also in previous version of rpm."

So I think we should remove the '%triggerun -- %{name} < 1:1.5.0-22', because it might lead to some hard-to-reproduce problems when upgrading from RHEL-6.
We actually don't need it as the '< 1:1.5-0.9' trigger has already been correct.

[1] http://pkgs.fedoraproject.org/cgit/cups.git/commit/?id=d44ca3247c00727ecfc986027d847fe77c15250d
[2] http://pkgs.fedoraproject.org/cgit/cups.git/commit/?id=cb5964de441f16576888ef454b22a5ec5f7c1d83