Only merge external content once

Idbd223f1be72f8d207d707d9807e732a8c7b971a added a new regression
which causes no content to be displayed under some circumstances,
but only when using external store.

This removes the duplicated method call causing the issue.

Change-Id: I91d99ffd4063199a6f066858bdf970427f93aaf4
Merge "Only merge external content once"