grantAll timing behaviour inconsistent with grant

[Wolfgang Schnerring]

You can <grant> a permission that is defined by ZCML executed *after* the <grant>, like so:
  <grant role="some.Role" permission="MyPermission"/>
  <permission id="MyPermission" title="foo"/>
But a <grantAll> will *not* pick up any permissions that are defined *after* the <grantAll>, like so:
  <grantAll role="some.Role"/>
  <permission id="MyPermission" title="foo"/>

In the first example, someRole will have MyPermission, in the second it will not.

The reason is that the grant-Directive just passes on the permission's ID (a string), while the grantAll-directive relies on enumerating all existing permissions (using getUtility()).

How could grantAll be made consistent with grant?