fix: correctly handle injecting environment variables to deployment tasks

Also test that release tasks are invoked the correct environment.

Closes #3817

tests/apps/dockerfile-release/project/asgi.py

@@ -0,0 +1,16 @@
+"""
+ASGI config for project project.
+
+It exposes the ASGI callable as a module-level variable named ``application``.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/3.0/howto/deployment/asgi/
+"""
+
+import os
+
+from django.core.asgi import get_asgi_application
+
+os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'project.settings')
+
+application = get_asgi_application()