Changing namespace of dmn file breaks links and shapes

When I change the namespace of a .dmn file, it is shown in the upper part of the file:

However, also stuff at the shapes is modified, breaking stuff:

As you can see, the old namespace appears in the new file. This also goes wrong at the edges.
In the visual representation, all those shapes and edges are not visible any longer.
When compiling, this results in a lot of warnings: