Error when trying to add/remove additional templates in the host mass update form

In Configuration->Hosts->Host mass update, in the Host mass update form select "Link additional templates", then click remove or add button ->
will appear the following error:

array_keys() expects parameter 1 to be array, string given [hosts.php:182]
Invalid argument supplied for foreach() [hosts.php:189]

Reproduced in the trunk rev #26719.