branchcache: move the processing of the new data in a dedicated method
In a future changeset, this will allow the V3 of the branch cache to use a fast
path when possible.
%include map-cmdline.default
[templates]
changeset = '{cset}{branches}{bookmarks}{tags}{lphase}{parents}{luser}{ldate}{summary}\n'
changeset_verbose = '{cset}{branches}{bookmarks}{tags}{lphase}{parents}{luser}{ldate}{lfiles}{lfile_copies_switch}{description}\n'