When on branch T, detach the HEAD at the base of the branch, and
find the newest iteration of the same topic from lore, apply the
patches, and show the range-diff from what we have.
Depends on having healty "amlog" notes to allow us identify what
patch message resulted in the commit T, and working "b4 am" and the
lore archive that lets us grab the latest iteration.
Junio C Hamano