---------- now follows much the same info in different words ----------
-1. git-debrebase [-i etc.]
-
- should:
- check for ffq-prev
- if is already a ffq-prev, fine, do no more
- if not:
-
- check our origin branch exists and we are ff from it
- if not fail
-
- check our other might-be-pushed to branches
- check we are ff from them
- if not fail
-
- set ffq-prev to something which is ff from
- all above branches
-
- we use our tip, as discussed above
- (optionally, can use some other commit which is ff
- from all of the above, eg one of them)
-
N. git-debrebase [--noop-ok] record-ffq-prev
does what is described above