py3: use dict.update() instead of constructing lists and adding them dict.items() returned a list on Python 2 and whereas on Python 3 it returns a view object. So we required a work around. Using dict.update() is better then constructing lists as it should save us on gc churns.

patchbomb: add -B option to select a bookmark Add the -B/--bookmark option to select a bookmark whose changesets and its ancestors will be selected unless a new bookmark/head is found. This is inspired by hg strip -B option.

test: add the mirror push race case for non-contiguous branch head We check case where the raced push update that a head through another named branch while the racing push update that same head.

test: add a push race case where non-contiguous branch head are created We check case where the raced push an update to branch default head while the racing push update that same head but through another named branch.