Createsuperuser pre-start: don't do that when _any_ users exist in the DB

Fixes #54

bsmain/management/commands/prestart.py

@@ -12,17 +12,25 @@ User = get_user_model()
 class Command(BaseCommand):
     help = "Pre-start command to run before the server starts."
 
-    def handle(self, *args, **options):
-        if os.getenv("CREATE_SUPERUSER", ""):
+    def _create_superuser_if_needed(self):
+        if not os.getenv("CREATE_SUPERUSER", ""):
+            return
+
         if ":" not in os.getenv("CREATE_SUPERUSER"):
             raise ValueError("CREATE_SUPERUSER should be in the format 'username:password'")
 
         username, password = os.getenv("CREATE_SUPERUSER").split(":")
 
-            if not User.objects.filter(username=username).exists():
+        if User.objects.all().exists():
+            print("Superuser not created: user(s) already exist.")
+            return
+
         User.objects.create_superuser(username=username, password=password)
         print(f"Superuser created: {username}")
 
+    def handle(self, *args, **options):
+        self._create_superuser_if_needed()
+
         # Similar considerations apply here as those which are documented in bugsink.views._phone_home().
         # By putting this in prestart, we add one more location to the list of kick-off locations; with the added
         # benefit that this particular location also gives some signal for (Docker) installations that are prematurely