obsolete: explicitly track folds inside the markers We now record information to be able to recognize "fold" event from obsolescence markers. To do so, we track the following pieces of information: a) a fold ID. Unique to that fold (per successor), b) the number of predecessors, c) the index of the predecessor in that fold. We will now be able to create an algorithm able to find "predecessorssets". We now store this data in the generic "metadata" field of the markers. Updating the format to have a more compact storage for this would be useful. This way of tracking a fold through multiple markers could be applied to split too. This would have two advantages: 1) We get a simpler format, since number of successors is limited to [0-1]. 2) We can better deal with situations where only some of the split successors are pushed to a remote repository. We should look into the relevance of such a change before updating the on-disk format. note: unlike splits, folds do not have to deal with cases where only some of the markers have been synchronized. As they all share the same successor changesets, they are all relevant to the same nodes.