-# automatic case
-# git-debrebase new-upstream
-# - previous breakwater merge must be gdr-generated
-# - orig set is the same as before
-# - implicitly uses upstream branches according to orig set
-# - not all upstream branches need be updated
-# - insists on fast-forward of each branch, unless
-# --force (or --force=<subdir>[/])
-# branch set adjustments
-# git-debrebase new-upstream --add <subdir>/
-# git-debrebase new-upstream --rm <subdir>/
-# git-debrebase new-upstream / [<subdir>/ ...]
-# - orig set is adjusted
-# - otherwise like auto (--add is not checked for ffness, obv)
-# - multiple --add and --rm may be specified
-# - --add makes new upstream the last contributor
-# explicit
-# git-debrebase / [<rootcommitid>] [<subdir>/ [<commitid>] ...]
-# - orig set is precisely as specified now
-# - previous breakwater merge is irrelevant
-# - no fast forward checks
-# for now only explicit with commitids
-
-# implicitly uses `upstream'
-# # (or multiple other branches)
-# git-debrebase new-upstream \
-# [<subdir>/]=<commitid>
-
-# UPSTREAM[,[[SUBDIR:]SUBUPSTREAM]
-# default for SUBDIR: is from previous upstream merge[xxx terminology]
-#