The following line has a reference to an undefined variable `changedIDs`:
As a result in some cases when removing parts of the pedigree some code which is expected to run does not, which may cause all random kinds of problems. The error was silently eaten by a try-catch block, and I can not find an example which results in clearly visible problems, but this is obviously a bug
when the relationship marked with red circle is removed from the pedigree on the picture below, one of the lines which is crossed by another line is being removed, which triggers the code which had a bug (and a new fix, which should also be tested):
fyi I recreated the same pedigree and removed relationship marked in red in both rc1 and PR, the result was identical and weird looking (although correct).