small fix for cbox-build

cbox-tree.d/usr/lib/cryptobox/configure-cryptobox.sh

@@ -71,8 +71,11 @@ function configure_normal()
 	   done
 	 done
 
-	 # remove deb-files, that were left by dfsbuild
-	 [ -d /opt/packages ] && rm -r /opt/packages
+	# remove deb-files, that were left by dfsbuild
+	test -d /opt/packages && rm -r /opt/packages
+
+	# set exitcode to zero
+	true
 }