Now that we have a global webhook, users can no longer see the HTTP
responses from the Manager.  If a tag is unexpectedly ignored for any
reason, the user will have to ask us to look in our logs.

This probably isn't much of a problem for tags generated by
git-debpush since in that case we'd need to investigate anyway.

But users who write their own tag generator will probably want it.

Ian.

(filing against dgit-infrastructure but this would be implemented in
tag2upload-service-manager.)