!10 fix post error when update versions

From: @eaglegai 
Reviewed-by: @seuzw 
Signed-off-by: @seuzw

arptables.spec

@@ -1,6 +1,6 @@
 Name:             arptables
 Version:          0.0.5
-Release:	  4
+Release:	  5
 Summary:          Administration tool for arp packet filtering
 
 License:          GPLv2+
@@ -40,17 +40,24 @@ install -p -D -m 755 %{SOURCE1} $RPM_BUILD_ROOT%{_libexecdir}/
 install -p -D -m 644 %{SOURCE2} $RPM_BUILD_ROOT%{_unitdir}/arptables.service
 mkdir -p $RPM_BUILD_ROOT%{_sysconfdir}/sysconfig
 echo '# Configure prior to use' > $RPM_BUILD_ROOT%{_sysconfdir}/sysconfig/%{name}
+ln -s arptables-legacy $RPM_BUILD_ROOT/%{_sbindir}/arptables
 
 %post
 %systemd_post %{name}.service
-update-alternatives --install /usr/sbin/arptables arptables /usr/sbin/arptables-legacy 10
 
 %preun
 %systemd_preun %{name}.service
 
 %postun
+if [ $1 -eq 1 ] && [ -x /usr/sbin/arptables-legacy ] && [ ! -h /usr/sbin/arptables ];then
+ln -s /usr/sbin/arptables-legacy /usr/sbin/arptables
+fi
 %systemd_postun_with_restart %{name}.service
-update-alternatives --remove arptables /usr/sbin/arptables-legacy
+
+%posttrans
+if [ -x /usr/sbin/arptables-legacy ] && [ ! -h /usr/sbin/arptables ];then
+ln -s /usr/sbin/arptables-legacy /usr/sbin/arptables
+fi
 
 %files
 %license COPYING
@@ -64,6 +71,12 @@ update-alternatives --remove arptables /usr/sbin/arptables-legacy
 %{_mandir}/man8/*.gz
 
 %changelog
+* Sat Jun 25 2022 gaihuiying <eaglegai@163.com> - 0.0.5-5
+- Type:bugfix
+- Id:NA
+- SUG:NA
+- DESC:fix post error when update versions
+
 * Sat Aug 28 2021 gaihuiying <gaihuiying1@huawei.com> - 0.0.5-4
 - Type:bugfix
 - Id:NA