LdapLogin developer has found a bug: disabling the Login plugin within the LdapLogin activate() method, will not disable the Login plugin.
Let's fix it since it will solve the nice use case: when LdapLogin is enabled, the default Login plugin is disabled. When it Ldap is disabled, back to using default Login plugin... nice!
In 4f9faf441d12e7d58b3450d0359b7bfa688a4493: Refactor Manager around enable/disable of plugins: Fixes #4529 Login plugin can be enabled/disabled ie. when disabling/enabling LoginLdap was reported in http://forum.piwik.org/read.php?9,109016
Thank you! Tested and confirmed as fixed.