laravel/framework — pull request #6056 by Edgpaez (2014-10-13 02:29:52+00:00)
Title: Skip database validation if attribute has already failed

Related to [#6048](https://github.com/laravel/framework/issues/6048)

In Postgres the existence validation raises an exception when comparing a string agains an integer column. This commits skips the database validator when the attribute has already failed, avoiding the exception.