Some documents are migrated to unexpected spaces when the expected target exists

Given the Movies and Movies.StarTrek spaces and a Movies.Spock document with parent Movies.StarTrek.WebHome, Movies.Spock is first migrated to Movies.StarTreck.Spoke.WebHome, as expected.

But a second migration will find that Movies.StarTrek.Movies.Spock.WebHome exists, and the code tries to be clever and migrates this page to Movies.StarTrek.Movies.Spock.WebHome instead of Movies.StarTrek.Spock_2.WebHome.

The clever part of the code is still useful, but it needs to be disabled for such cases, basically when the root space between the original document and the target are shared - we don't want the root space to be repeated.