OOPS when daily build targets unsupported distroeries

A user is building a recipe that targets maverick, which is no longer supported. Doing this triggers an OOPS:

  BuildNotAllowedForDistro: A build against this distro is not allowed.

    Traceback (most recent call last):
  Module zope.publisher.publish, line 134, in publish
    result = publication.callObject(request, obj)
  Module lp.services.webapp.publication, line 499, in callObject
    return mapply(ob, request.getPositionalArguments(), request)
  Module zope.publisher.publish, line 109, in mapply
    return debug_call(obj, args)
   - __traceback_info__: <bound method SourcePackageRecipeRequestDailyBuildView.__call__ of <zope.browserpage.metaconfigure.SourcePackageRecipeRequestDailyBuildView object at 0x13bab9d0>>
  Module zope.publisher.publish, line 115, in debug_call
    return obj(*args)
  Module lp.services.webapp.publisher, line 420, in __call__
    self.initialize()
  Module lp.app.browser.launchpadform, line 136, in initialize
    self.form_result = form_action.success(data)
  Module zope.formlib.form, line 606, in success
    return self.success_handler(self.form, self, data)
  Module lp.code.browser.sourcepackagerecipe, line 544, in build_action
    builds = recipe.performDailyBuild()
  Module lp.code.model.sourcepackagerecipe, line 328, in performDailyBuild
    distroseries, PackagePublishingPocket.RELEASE)
  Module lp.code.model.sourcepackagerecipe, line 293, in requestBuild
    raise BuildNotAllowedForDistro(self, distroseries)
BuildNotAllowedForDistro: A build against this distro is not allowed.