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Re: [PATCH] rebase --abort: cleanup refs/rewritten

Hi Dscho

On 30/04/2019 23:49, Johannes Schindelin wrote:
Hi Phillip,

On Tue, 30 Apr 2019, Phillip Wood wrote:

On 29/04/2019 17:07, Johannes Schindelin wrote:

On Fri, 26 Apr 2019, Phillip Wood wrote:

From: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>

When `rebase -r` finishes it removes any refs under refs/rewritten
that it has created. However if the rebase is aborted these refs are
not removed. This can cause problems for future rebases. For example I
recently wanted to merge a updated version of a topic branch into an
integration branch so ran `rebase -ir` and removed the picks and label
for the topic branch from the todo list so that
      merge -C <old-merge> topic
would pick up the new version of topic. Unfortunately
refs/rewritten/topic already existed from a previous rebase that had
been aborted so the rebase just used the old topic, not the new one.

Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>

Makes a ton of sense, and I feel a bit embarrassed that I forgot about
that item on my TODO list. The patch looks obviously correct!

Thanks, after I sent it I realized that --quit should probably clear
refs/rewritten as well, so I'll re-roll with that added. (One could argue that
a user might want them after quitting the rebase but there is no way to clean
them up safely once we've deleted the state files and I suspect most users
would be suprised if they were left laying around)

I am not so sure. `--quit` is essentially all about "leave the state
as-is, but still abort the rebase".

I think it depends on what you mean by "state" `--quit` is about removing state specific to rebases while preserving HEAD, the index and worktree. When "rebase --quit" was introduced in 9512177b68 ("rebase: add --quit to cleanup rebase, leave everything else untouched", 2016-11-12) the start of the log message reads

    rebase: add --quit to cleanup rebase, leave everything else untouched

    There are occasions when you decide to abort an in-progress rebase and
    move on to do something else but you forget to do "git rebase --abort"
    first. Or the rebase has been in progress for so long you forgot about
    it. By the time you realize that (e.g. by starting another rebase)
    it's already too late to retrace your steps. The solution is normally

        rm -r .git/<some rebase dir>

    and continue with your life.

So `--quit` is used when the user has forgotten to run "rebase --abort". They have moved onto something else and want to remove the rebase state without changing the current HEAD, index or worktree, they are not looking to use the refs under refs/rewritten. I think the refs rebase creates under refs/rewritten is an implementation detail of "rebase -r" and should be treated like files under .git/rebase-merge. I'm worried that if we leave them lying around after --quit they will cause trouble for future rebases in the same way they have after "rebase --abort"

Best Wishes


So if I were you, I would *not* remove the `refs/rewritten/` refs in the
`--quit` case.