+========================================
+
+So, pm handling specifics:
+
+strategy is to avoid making needless pseudomerges
+pseudomerges that exist will be preserved
+(by being included in will-overwrite)
+
+This is good because the presence of a pseudomerge means we know we
+want to keep it; and that allows explicit control over history detail
+level.
+
+It does mean we must avoid making the pseudomerges unnecessarily.
+They should be made just before (ideally, part of) dgit push.
+
+1. git-debrebase [-i etc.]
+
+ should:
+ check for will-overwrite
+ if is already a will-overwrite, 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 will-overwrite 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
+
+2. git-debrebase [--noop-ok] stitch
+
+ makes pseudomerge with will-overwrite
+ deletes will-overwrite
+
+ we will teach dgit to do
+ git-debrebase stitch
+
+3. git-debrebase push
+
+ like git push only does stitch first
+ ??? command line parsing!
+
+4. git-debrebase release
+
+ stiches, finalises changelog, signs tags, pushes everything
+ for the future, when there is some automatic builder
+
+will-overwrite for each ref
+ refs/heads/FOO
+is
+ refs/ffq-prev/FOO
+
+========================================
+
+import from gbp
+
+[ all this is done now:
+ inputs:
+ current HEAD (patches-unapplied),
+ this is going to be the base of the old breakwater
+ nominated upstream
+
+ checks:
+ HEAD:<upstream> = upstream:<upstream>
+ upstream..HEAD:<upstream> is empty (overrideable)
+ upstremm:debian is empty (overrideable)
+
+ procedure:
+ construct
+ run gbp pq import to generate pq branch
+ new breakwater is
+ old HEAD
+ commit to remove d/patches
+ breakwater pseudomerge with upstream
+ "rebase" of pq branch, each commit with d/patches stripped
+]
+
+what about dgit view branch ?
+ideally, would make pseudomerge over dgit view
+would need to check that dgit view is actually dgit view of
+ ond of our ancestors
+failing that first push will need --overwrite
+
+========================================
+
+divergence, merges:
+
+same problem
+ if merge, look at branches before merge
+ generate new combined branch
+ pseudomerge to overwrite merge
+
+current avaiable strategies:
+
+ maybe launder foreign branch
+
+ if foreign branch is nmuish, can rebase it onto ours
+
+ could merge breakwaters (use analyse to find them)
+ merge breakwaters (assuming same upstream)
+ manually construct new patch queue by inspection of
+ the other two patch queues
+
+ instead of manually constructing patch queue, could use
+ gbp pq export and git merge the patch queues
+ (ie work with interdiffs)
+
+ if upstreams are different and one is ahead
+ simply treat that as "ours" and
+ do the work to import changes from the other
+
+ if upstreams have diverged, can
+ resolve somehow to make new upstream
+ do new-upstream on each branch separately
+ now reduced to previously "solved" problem
+
+ in future, auto patch queue merge algorithm
+ determine next patch to apply
+ there are three versions o..O, l..L, r..R
+ we have already constructed m (previous patch or merged breakwater)
+ try using vector calculus in the implied cube and compute
+ multiple ways to check consistency ?