Index: wp-admin/includes/upgrade.php
===================================================================
--- wp-admin/includes/upgrade.php	(revision 23297)
+++ wp-admin/includes/upgrade.php	(working copy)
@@ -1566,7 +1566,7 @@
 
 				// Get the default value from the array
 					//echo "{$cfields[strtolower($tablefield->Field)]}<br>";
-				if (preg_match("| DEFAULT '(.*)'|i", $cfields[strtolower($tablefield->Field)], $matches)) {
+				if (preg_match("| DEFAULT '([^']*)'|i", $cfields[strtolower($tablefield->Field)], $matches)) {
 					$default_value = $matches[1];
 					if ($tablefield->Default != $default_value) {
 						// Add a query to change the column's default value