fix bug that caused flavors to be permanently deleted
diff --git a/planetstack/core/admin.py b/planetstack/core/admin.py
index 7fa537a..be75f75 100644
--- a/planetstack/core/admin.py
+++ b/planetstack/core/admin.py
@@ -609,7 +609,7 @@
         # so well handle that manually here
         for flavor in deployment.flavors.all():
             if getattr(flavor, 'name') not in self.cleaned_data['flavors']:
-                flavor.delete()
+                deployment.flavors.remove(flavor)
         for flavor in self.cleaned_data['flavors']:
             if flavor not in deployment.flavors.all():
                 flavor.deployments.add(deployment)