Ben Knoble [off-list ref] writes:
quoted
* merge parent numbers are 2-based (sanity of this statement is
already questionable). If HEAD is a merge, HEAD~2 is the
"(first) side branch that was merged", HEAD~3 is the "(second)
side brnach that was merged (in an octopus merge), and so on.
HEAD^2, 3, etc., rather? :)
Thanks for correcting me. Yes. And HEAD^1 is the first parent that
is the same as HEAD~1.