If one uses `git debpush --gbp` for a tree where dgit can already detect
that the package uses gbp-pq(1) patches (I think by looking at the last
tag in the history?), then the tool complains at you that the option was
superfluous.  A comment indicates that this is to get people into the
habit of just typing `git debpush` for their regular uploads.

However, if one is obediently in that habit, then uploads can fail as
shown in the forwarded email.  The previous upload of pydantic
(2.13.4-1) had no patches and so dgit did not require any kind of
--quilt argument.  2.13.4-2 added patches.  I used `git debpush`, which 
appeared completely happy on the client side, but resulted in a failure
from tag2upload.

Right now, it is in practice safer for users who know that their package
either uses gbp-pq(1) now or would use it if it had any patches (due to
team policy or whatever) to always use `git debpush --gbp` and ignore
the warning.  It seems that that isn't what you want, though, so I think
`git debpush` needs to detect the situation where the previous tag had
no quilt mode but the current tag requires one.

Thanks,