Removed staff members who had "Manage shops" permission can still create development stores

Details: It's been found that staff members of an organization in partners.shopify.com can have a permission to manage shops and those with that permission can create development stores that will be associated with the organization.

<form action="https://app.shopify.com/services/signup/setup" method=post>
<input name="utf8" value="Γ£ô">
<input name="authenticity_token" value="67uDHcA5IBtc1CRcl3teDJND+2w8ahtpbNo4aux93TfHq0MkadWVOPG0h/8Z+jjcWpXw96fX1BbnYTLiG9aqDw==">
<input name="signup[shop_name]" value="NewStoreTestTest1234"> …