Re: [PATCH v1] rebase -m: Use empty tree base for parentless commits

Fabian Ruch [off-list ref] writes:

quoted

The interface to "git-merge-$strategy" is designed in such a way
that each strategy should be capable of taking _no_ base at all.

The merge strategies "resolve" and "octopus" seem to refuse to run if no
base is specified. The former silently exits if no bases are given and
the latter dies saying "Unable to find common commit".

That just means these two strategies are not prepared to do a merge
without base (yet).  It does not automatically give license to the
caller to pass a random tree as if it is the merge base the user
wanted to use.

For "resolve", I think it is OK for it to detect that the caller did
not give a common ancestor tree and use an empty tree when merging
(which is what merge-recursive ends up doing internally).

I am not offhand sure if the same is sensible for "octopus", though.