Fix purge action in folder manager (#1489280)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix purge action in folder manager (#1489280)
 - Fix image scaling issues when image has only one dimension smaller than the limit (#1489274)
 - Fix issue where uploaded photo was lost when contact form did not validate (#1489274)
 - Fix base URL resolving on attribute values with no quotes (#1489275)

program/js/app.js

@@ -398,7 +398,7 @@ function rcube_webmail()
         }
         else if (this.env.action == 'edit-folder' && this.gui_objects.editform) {
           this.enable_command('save', 'folder-size', true);
-          parent.rcmail.env.messagecount = this.env.messagecount;
+          parent.rcmail.env.exists = this.env.messagecount;
           parent.rcmail.enable_command('purge', this.env.messagecount);
           $("input[type='text']").first().select();
         }