epm-downgrade: install rpm files with --oldpackage

bin/epm-downgrade

@@ -77,16 +77,20 @@ epm_downgrade()
 	case $PMTYPE in
 	apt-rpm)
 		local APTOPTIONS="$(subst_option non_interactive -y)"
-		__epm_add_alt_apt_downgrade_preferences || return
 		# pass pkg_filenames too
 		if [ -n "$pkg_names" ] ; then
+			__epm_add_alt_apt_downgrade_preferences || return
 			load_helper epm-install
 			(pkg_names=$pkg_names epm_install)
+			__epm_remove_apt_downgrade_preferences
+		elif [ -n "$pkg_files" ] ; then
+			load_helper epm-install
+			(pkg_files=$pkg_files force="$force --oldpackage" epm_install)
 		else
+			__epm_add_alt_apt_downgrade_preferences || return
 			load_helper epm-upgrade
 			epm_upgrade "$@"
 		fi
-		__epm_remove_apt_downgrade_preferences
 		;;
 	apt-dpkg)
 		local APTOPTIONS="$(subst_option non_interactive -y)"