Ancestor FC fixing rfc

Currently, when a file is deleted, the Ancestor/daughter business does not work any more because a file in the chain is missing. When a file is being deleted, it's necessary to fix somehow the relationships. There are 2 options:

1. either the relationship is simply removed and the depth is unchanged: a file would then have

file1 1 
  file2 2
    file4 4

in the case file3 was removed

2. the relationship is removed, and the depth is fixed, such that in the example above, one would have

file1 1 
  file2 2
    file4 3

in the case file3 was removed.

I would be in favor of 2...