installer: check for process instead of locks

scripts/installer.sh

@@ -24,7 +24,8 @@ function prepare_apt_once() {
     log "Making sure apt is in a good state"
 
     log "Waiting for all dpkg tasks to finish..."
-    while fuser /var/lib/dpkg/lock; do
+    # we used to check for locks, but there are many locks it seems
+    while pgrep -x "apt-get|apt|dpkg" >/dev/null; do
         sleep 1
     done