qmsystem: disable tests *before* configuring

recipes-nemomobile/qmsystem/qmsystem_git.bb

@@ -13,7 +13,7 @@ inherit qmake5
 B = "${S}"
 
 # Disable tests which don't work as expected
-do_configure_append () {
+do_configure_prepend () {
     sed -i "s@system keyd tests@system keyd@" libqmsystem2.pro
 }