Issue 1

Snap promote does not allow specifying a specific revision number to promote. Only a source channel and destination channel.

Issue 2

snap info only list the main channels, not the sub-channels (branches), so there is no way to test the workflow without modifying the main channels.

Re 1: Use release rather than promote.

$ snapcraft release -h
Usage:
    snapcraft release [options] <name> <revision> <channels>

Release at to the selected store .