Use maybe_unserialized on all post_meta values on import to ensure we don't end up with double serialized data in the database. Fixes #10619 props znarfor.

git-svn-id: http://svn.automattic.com/wordpress/trunk@12495 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/import/wordpress.php

@@ -605,6 +605,8 @@ class WP_Import {
 			$key   = $this->get_tag( $p, 'wp:meta_key' );
 			$value = $this->get_tag( $p, 'wp:meta_value' );
 			$value = stripslashes($value); // add_post_meta() will escape.
+			// get_post_meta would have done this but we read straight from the db on export so we could have a serialized string
+			$value = maybe_unserialize($value);
 			
 			$this->process_post_meta($post_id, $key, $value);