The grilo-plugins build has started to fallback to downloading grilo
as a subproject if certain dependencies aren't met [1]. In this case,
the grilo-pls-0.3 dependency is missing because it's disabled in the
grilo build via the -Denable-grl-pls=false option.

This is a problem because network access is not available in the build
sandbox.

[1] grilo-plugins commit 34d3c5844864f0d0
    grilo-plugins!68

!124