When copy `n paste inserting additional text into an existing content with a rich text field, the integrated links are preceded by an "http". This will cause an error when publishing.

Steps to reproduction:

-create new content e.g. article

• in the rich text field create a content with internal link to a node and a link with mail address (mailto).
• Publish content
• Edit content and insert a new paragraph with text by copy 'n paste
  => before the links above a http was inserted which leads to a validation error when saving.