import: allow processing of extra part header during import As we have a way for extension to add more header, we need a way for them to actually process them. We add a basic hook points to alter the changeset (especially extra) before we commit. There would be more to do for a full featured hooking, but this currently fit my needs.

extract: parse 'nodeid' using the generic mechanism Parsing 'nodeid' is very simple and a good first test.

extract: parse 'branch' using the generic mechanism Parsing 'branch' is very simple and a good first test.