Custom tags are removed, if empty lines are removed from the end of a XML Block

Steps to reproduce

• Using chrome (windows or mac)
• Create a content as the following (<empty line> is an empty line)

  This
  <custom name="underline">underline</custom>
  tag
  <empty line>
  

• Publish
• Edit
• Remove the empty line from the end (focus on the empty line and press backspace)
  => Expected result: the empty line will be removed. The remaining won't be affected
  => Actual result: underline will no longer be underline