simulate: it is ok to run with empty list

bin/epm-simulate

@@ -23,11 +23,11 @@ load_helper epm-install
 epm_simulate()
 {
     local CMD
-    [ -n "$pkg_filenames" ] || fatal "Run $epm_cmd without packages"
+    [ -z "$pkg_filenames" ] && echo "Skip empty list" && return 0
 
     local filenames="$(echo $pkg_filenames | filter_out_installed_packages)"
     # FIXME: can't correct receive status 2 in mandriva?
-    [ -z "$filenames" ] && echo "Skip empty simulate list" && return 0 #&& return 2
+    [ -z "$filenames" ] && echo "All packages are already installed" && return 0 #&& return 2
 
     case $PMTYPE in
     	apt-rpm|apt-dpkg)