Editor breaks rxml:edit-lock

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=3842

Reported by Marcus Wellhardh wellhard@roxen.com

The following locked part of a component:

  <variant rxml:edit-lock='yes'>7</variant>

Transformes to the following after edit and save in the insite editor:

  <variant NS0:edit-lock='yes' xmlns:NS0='rxml:'>7</variant>

The lock is no longer effective. The problem happens on both IE and Firefox.

Reported in [RT#5819].