The test_form_creates_new_repositories test was failing because the form's repositories field had an empty queryset when creating new hackathons, preventing valid repository selections from passing validation.

Root Cause

In HackathonForm.__init__, the repositories queryset was unconditionally set to Repo.objects.none() for new instances:

if self.instance.pk and self.instance.organization:
    self.fields["repositories"].queryset = Repo.objects.filter(...)
else:
    self.fields["repositories"].queryset = Repo.objects.none()  # ❌ Too restrictive

Django validates form choices against the field's queryset before calling clean_repositories(), so the form would fail validation with "Select a valid choice. X is not one of the available choices" even when selecting valid repositories from the chosen organization.

Changes

Updated __init__ to populate the repositories queryset from the organization in the form data:

else:
    organization_id = None
    if "data" in kwargs and kwargs["data"]:
        organization_id = kwargs["data"].get("organization")
    
    if organization_id:
        self.fields["repositories"].queryset = Repo.objects.filter(organization_id=organization_id)
    else:
        self.fields["repositories"].queryset = Repo.objects.none()

This allows existing repositories from the selected organization to be validated and selected when creating new hackathons.

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