A delivery keyed by commit stayed stopped forever once an earlier, closed
duplicate pull request with the same head had stopped it, even though a
later pull request went on to merge that very commit: the merge only set
merged_as on the stopped record, and the walk that carried it waited for
this owner's word with no delivery left to give it. PullUpdated and
PullMerged now start such a delivery over, under the same id, for the
pull request that announces or merges it next, naming both pull requests
in the transition's why. Any other stop (a person's, a group's, the same
pull request's own close) is untouched.
jochen
9e8521afb5