const name should be upper case

smash/web/migration_functions.py

 from django.conf import settings
 
-db_name = 'default'
-db_backend = settings.DATABASES[db_name]['ENGINE'].split('.')[-1]
+DB_NAME = 'default'
+DB_BACKEND = settings.DATABASES[DB_NAME]['ENGINE'].split('.')[-1]
 
 
 def is_sqlite_db():
-    return db_backend == 'sqlite3'
+    return DB_BACKEND == 'sqlite3'