(ie the semantics in the git-debrebase model)
for each commit.
+=item git-debrebase record-ffq-prev
+
+Establishes the current branch's ffq-prev,
+as discussed in L</UNSTITCHING AND LAUNDERING>,
+but does not launder the branch or move HEAD.
+
+It is an error if the ffq-prev could not be recorded.
+It is also an error if an ffq-prev has already been recorded,
+unless --noop-ok.
+
=item git-debrebase launder-v0
Launders the branch without recording anything in ffq-prev.