pull: improve advice for unconfigured error case
There are several reasons a git-pull invocation might not
have anything marked for merge:
1. We're not on a branch, so there is no branch
2. We're on a branch, but there is no configuration for
3. We fetched from the configured remote, but the
configured branch to merge didn't get fetched (either
it doesn't exist, or wasn't part of the fetch refspec).
4. We fetched from the non-default remote, but didn't
specify a branch to merge. We can't use the configured
one because it applies to the default remote.
5. We fetched from a specified remote, and a refspec was
given, but it ended up not fetching anything (this is
actually hard to do; if the refspec points to a remote
branch and it doesn't exist, then fetch will fail and
we never make it to this code path. But if you provide
a wildcard refspec like
then you can see this failure).
We have handled (1) and (2) for some time. Recently, commit
a6dbf88 added code to handle case (3).
This patch handles cases (4) and (5), which previously just
fell under other cases, producing a confusing message.
While we're at it, let's rewrap the text for case (3), which
looks terribly ugly as it is.
Signed-off-by: Jeff King <firstname.lastname@example.org>
Signed-off-by: Junio C Hamano <email@example.com>