Problems with relation

The relation 17501 contains the German motorway “A 4”. Another user reported that it’s impossible to upload this relation. I tried to find out why.
After downloading the complete relation I found two strange things:

  • There’s a way in the relation with 0 nodes. If you browse that way you will see, that it contains 3 nodes. These 3 nodes are all already deleted if you take a closer look at them.
  • There are 7 ways in the relation which still stay “incomplete” after downloading all members of the relation.

If you try to upload the relation, e.g. after deleting the incorrect members mentioned above, then you will receive the message “412: Precondition Failed” in JOSM.

What might be the problem here?