Re: [PATCH 1/2] t/t5510: demonstrate failure to fetch when current branch has merge ref

Brandon Casey [off-list ref] writes:

From: Brandon Casey <redacted>

When 'git fetch' is supplied just a repository URL (not a remote name),
and without a fetch refspec, it should fetch from the remote HEAD branch
and update FETCH_HEAD with the fetched ref.  Currently, when 'git fetch'
is called like this, it fails to retrieve anything, and does not update
FETCH_HEAD, if the current checked-out branch has a configured merge ref.

i.e. this fetch fails to retrieve anything nor update FETCH_HEAD:

   git checkout master
   git config branch.master.merge refs/heads/master
   git fetch git://git.kernel.org/pub/scm/git/git.git

Hmph, we can call it a regression, since we certainly won't see this
failure with versions of git that is unaware of branch.*.merge.

But what should we be expecting?

Just as a datapoint, an ancient git (e.g. v1.4.0), the above command line
would have fetched the HEAD from the remote side, no matter what that
symref is pointing at.  Your [2/2] patch replicates this behaviour, which
is fine by me [*1*].

Your test only checks if we leave _anything_ in FETCH_HEAD, and does not
check if we only fetch one, if we fetch all the refs, or if we fetch what
the configuration branch.*.merge asks for (but without the corresponding
branch.*.remote configuration, doing so is pointless).

I think it would be better to have two tests.  One arranges the current
branch to track the same branch the HEAD at the remote points at, and the
other arranges the current branch to track a branch different from the
HEAD at the remote points at.  In both cases, as "fetch" should ignore the
configuration, we should get the object pointed by the HEAD on the remote
side.

Thanks.


[Footnote]

*1* A plausible alternative is to match the given URL against list of
existing remote.<name>.url (make sure there is only one), and behave as if
that the remote name is given.  I can be persuaded either way, but not
looking at the configuration feels a lot simpler to explain and understand
(i.e. "with name, we use the set of configuration variable given to that
name; without name, there is no configuration for us to look up").