mailto is not stripped when editing a link to an e-mail address

Follow this steps to reproduce:

• Edit a new page in wiki mode and set the content to:

  before [[label>>mailto:me@myself.com]] after
  

• Save and edit the page in WYSIWYG mode
• Edit the link. The "Email Address" field is set to "mailto:me@myself.com". It should be only "me@myself.com"
• Click "Create Link" and switch to Source tab. The content is:

  before [[label>>mailto:mailto:me@myself.com]] after
  

  As you can see "mailto" is duplicated.