An anonymous remote wouldn't create remote-tracking branches, so testing
we don't create them for TAGS_ALL is nonsensical. Furthermore, the name
of the supposed remote-tracking branch was also not one which would have
been created had it had a name.

Give the remote a name and test that we only create the tags when we
pass TAGS_ALL and that we do create the remote-branch branch when given
TAGS_AUTO.

remote: accept a repo and name for renaming

Remote objects are not meant to be changed from under the user. We did
this in rename, but only the name and left the refspecs, such that a
save would save the wrong refspecs (and a fetch and anything else would
use the wrong refspecs).

Instead, let's simply take a name and not change any loaded remote from
under the user.

This function does not in fact tell us anything, as almost anything with
a colon in it is a valid rsync-style SSH path; it can not tell us that
we do not support ftp or afp or similar as those are still valid SSH
paths and we do support that.

remote: accept a repository and remote name for deletion

We don't need the remote loaded, and the function extracted both of
these from the git_remote in order to do its work, so let's remote a
step and not ask for the loaded remote at all.

This fixes #2390.

When a list of refspecs is passed to fetch (what git would consider
refspec passed on the command-line), we not only need to perform the
updates described in that refspec, but also update the remote-tracking
branch of the fetched remote heads according to the remote's configured
refspecs.

These "fetches" are not however to be written to FETCH_HEAD as they
would be duplicate data, and it's not what the user asked for.

This lets us test this bit as well as getting closer to what they were
trying to do.

With opportunistic ref updates, git has introduced the concept of having
base refspecs *and* refspecs that are active for a particular fetch.

Let's start by letting the user override the refspecs for download.