setup: display return code information about failed `hg` call This help to understand what is going wrong when things goes wrong.

bundlespec: rationalize the way we specify stream bundle version Instead of having weird dedicated option for each version (v2, v3, etc) we reuse the same "stream" parameters. This is consistent with the ability to request a stream clone using "none-v2;stream=v2". This changeset introduce no user visible change, this is pure internal cleaning.