fix format_mdy_to_ymd() to leave '' as is

diff --git a/format.php b/format.php
index 451ba21..a6b0582 100644 (file)
--- a/format.php
+++ b/format.php
@@ -292,6 +292,7 @@ function format_dollars($str) {
 
 # date is edited as mm/dd/yyyy but stored as yyyy-mm-dd
 function format_mdy_to_ymd($str) {
+       if($str == '') return '';
        require_once('code/wfpl/time.php');
        return mdy_to_ymd(format_oneline($str));
 }