BugFix for a rare case:

BugFix for a rare case:
  when splitting a partition containing followers, these
  might stay on the "looser" side and must be constant-propagated
  then to allow them to split out.
  This might be a fix for a self-made problem. We do the follower ->
  leader transition on both sides while the original algo "might"
  do than on the winner side only...

[r22962]