The text on registration page is cut after applying invalid input

Prerequisites:

• have installed XWiki 16.10-RC
• extra user or existing one (Admin)

Steps to reproduce:

• If you authorize in your XWiki, then logout
• Access Registration form by pressing "Register" button on top menu
• Fill required fields, in "Username" input put existent username
• Press "Register" button
• Observe the page

Actual result:

You will have at the start cut sentence "up here so you can edit pages and participate in the wiki."

Expected result:

The text hasn't been cut and has full content "Sign up here so you can edit pages and participate in the wiki."