Re: [PATCH v3] rebase --merge: optionally skip upstreamed commits

> When rebasing against an upstream that has had many commits since the
> original branch was created:
> 
>  O -- O -- ... -- O -- O (upstream)
>   \
>    -- O (my-dev-branch)
> 
> it must read the contents of every novel upstream commit, in addition to
> the tip of the upstream and the merge base, because "git rebase"
> attempts to exclude commits that are duplicates of upstream ones. This
> can be a significant performance hit, especially in a partial clone,
> wherein a read of an object may end up being a fetch.
> 
> Add a flag to "git rebase" to allow suppression of this feature. This
> flag only works when using the "merge" backend.
> 
> This flag changes the behavior of sequencer_make_script(), called from
> do_interactive_rebase() <- run_rebase_interactive() <-
> run_specific_rebase() <- cmd_rebase(). With this flag, limit_list()
> (indirectly called from sequencer_make_script() through
> prepare_revision_walk()) will no longer call cherry_pick_list(), and
> thus PATCHSAME is no longer set. Refraining from setting PATCHSAME both
> means that the intermediate commits in upstream are no longer read (as
> shown by the test) and means that no PATCHSAME-caused skipping of
> commits is done by sequencer_make_script(), either directly or through
> make_script_with_merges().
> 
> Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
> This commit contains Junio's sign-off because I based it on
> jt/rebase-allow-duplicate.
> 
> This does not include the fix by Đoàn Trần Công Danh. If we want all
> commits to pass all tests (whether run by Busybox or not) it seems like
> we should squash that patch instead of having it as a separate commit.
> If we do squash, maybe include a "Helped-by" with Đoàn Trần Công Danh's
> name.