There is a set of information related to a merge which is needed on commit. We
want to store such information in the mergestate so that we can read it while
For this purpose, we are using merge records and introduced a merge
entry state for that. However this won't scale and is not clean way to implement
This patch reworks the existing logic related to this to use _stateextras and
read from it.
Right now the information stored is not very descriptive but it will be in next
Using _stateextras also makes MERGE_RECORD_MERGED_OTHER useless and only to be
kept for BC.