The -w option doesn't work so well with /usr/bin/env

dba/update-davical-database

@@ -1,9 +1,10 @@
-#!/usr/bin/env perl -w
+#!/usr/bin/env perl
 #
 # Update the DAViCal database by repeatedly applying patches to it
 # in the correct order.
 #
 
+use warnings;
 use strict;
 
 use DBI;