Mailman plugs test on the server url is too strict

The Mailman provisioning plugin tests that the REST API URL provided is a valid URL. Since I run my Mailman server in a docker container, the URL is http://mailman-core:8001 which is rejected as a valid URL (COmanage prints "string must not be blank"). The problem is the validator is too strict, which I patched with

{{--- Model/CoMailmanProvisionerTarget.php.orig 2020-04-16 21:57:19.212211495 +0000
+++ Model/CoMailmanProvisionerTarget.php 2020-04-16 21:57:38.529150313 +0000
@@ -50,7 +50,7 @@
'required' => true
),
'serverurl' => array(

• 'rule' => array('url', true),
  + 'rule' => 'notBlank',
  'required' => true,
  'allowEmpty' => false
  ),
  }}