Re: [BUG] rebase -p loses commits

Junio C Hamano [off-list ref] writes:

But the above "preserving" rewrite does not even preserve the topology of
the graph (the original * is a true merge between two forks, but *' is
not) to begin with.  Also, if you want to _usefully_ place F' on top of M,
such a rewrite should resolve possible conflicts that was resolved at * in
the original graph at F' anyway, which would mean that the resulting *'
should become a totally empty commit.

Why would anybody want to do such a thing to begin with?

Note that I am not saying "rebase -p" is not useful in general.  If you
had

         x---x---x---W---X
        /             \   \
    ---M               Y---Z

it is entirely sensible to want to have this history to exclude 'x'

         x---x---x---W---X
        /             \   \
    ---M---W'--X'      Y---Z
            \   \
             Y'--Z'

I think the patch I posted earlier should stop the problematic case Jeff
mentioned from happening, but I am trying to see if it makes sense to stop
without doing anything even when it is forced when onto and merge-base are
the same commit (which is not true for this "sensible" case).