epm update: fix getting package list (eterbug #17995)

bin/epm-list_available

@@ -43,7 +43,7 @@ epm_list_available()
 
     # use cache we got during epm update
     # TODO: update from this place if obsoleted
-    if [ -n "$short" ] ; then
+    if [ -n "$short" ] && [ -z "$update" ] ; then
         if [ -s $epm_vardir/available-packages ] ; then
             cat $epm_vardir/available-packages
             return

bin/epm-update

@@ -56,7 +56,7 @@ __save_available_packages()
 
     info "Retrieving list of all available packages (for autocompletion) ..."
     load_helper epm-list_available
-    short=--short epm_list_available | sort | sudorun tee $epm_vardir/available-packages >/dev/null
+    short=--short update=update epm_list_available | sort | sudorun tee $epm_vardir/available-packages >/dev/null
 }
 
 __epm_update_content_index()