Unfortunately, there isn't. This is a long standing problem, and one
that the app-refactor was looking into; however, that effort hasn't
come to fruition. Django's startup sequence is an area where some work
is required. The closest thing to a "signal" you're going to get is to
hook into the URL configuration, in the same way the admin
registration process does -- but it looks like you've tried that and
haven't had any luck.
One trick that I'm aware of that *might* work in your case is to force
the validation code to run in your production stack -- for example, as
a call in your WSGI container. From a functional perspective, this is
an expensive no-op. The validation won't ever return a different
result, which is why Django's WSGI handler doesn't call validate.
However, the process of validation *does* cause the startup sequence
to be a little more predictable, because the validation mechanism
imports *all* your app modules in your project in a predictable order.
If your problem is being caused by an unpredictable import order,
forcing a specific import order may work around your problem (or at
least make the side effects more predictable, and match the behaviour
of the development server).
Yours
Russ Magee %-)