Re: [PATCH v5] checkout: extend --track with a "fetch" mode to refresh start-point

[Junio C Hamano <gitster@pobox.com>]

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> A common workflow is:
>
>     git fetch origin
>     git checkout -b new_branch --track origin/some-branch
>
> The first command exists so the second sees an up-to-date view of the
> remote. If it is forgotten, origin/some-branch points at a stale
> commit and the new local branch is created from the wrong start
> point.

As I pointed out multiple times, I prefer not to see this called
"wrong".  Even if you did not "forget", somebody may be pushing
after you fetched and you may end up forking from a "stale" commit.
So not fetching is not inherently "wrong", simply because that is
how real world works.  Multiple people working in a distributed
environment does not give you absolute garantee that you will be "up
to date", ever, which makes it wrong to call anything that is not
"up to date" a "wrong starting point".

> This only matters when the user is setting up tracking and
> expects the new branch to start at the freshest tip; for a one-off
> checkout of an arbitrary commit there is no reason to "freshen" the
> start-point.

I do not think "arbitrary" fits in this workflow description.

If anything, "I'd take anything that the remote repository happens
to have at the tip, even without having a chance to sanity checke if
that is a good starting point" is more appropriate workflow to be
described with a word "arbitrary commit".

If you are checking out without forking from there, you'd more
likely be checking out the "latest" you have fetched from the other
side, often knowing exactly what it is after checking it with "git
show origin/$topic".

> Tie the new behavior to --track for that reason:

Notice that the reader hasn't heard what "the new behaviour" is up
to this point yet?

How about rewriting everything up to and including this "Tie the new
..." line perhaps like so:

    If you want to fork your topic branch from the very latest of
    the tip of a branch your remote has, you would do:

	git fetch origin some-branch
	git checkout -b new_branch --track origin/some-branch

    Extend the "--track" option of "git checkout" and allow users to
    write

	git checkout --track=fetch -b new_branch origin/some_branch

    to (1) fetch 'some-branch' from the remote 'origin', updating
    the remote-tracking branch 'origin/some-branch', (2) arrange
    subsequent 'git pull' on 'new_branch' to interact with
    'origin/some_branch' and (3) fork 'new_branch' from it.
   
    In the value of the '--track' option, 'fetch' can be combined
    with ...