Fix submodule fetching in trebuchet

At some point fetch && fetch --tags was replaces with fetch --all,
which doesn't do the same thing. This change reverts that code
so that recursive submodule checkout will again work correctly.

Change-Id: I8a878f4a79e0e6688bc7b98ab48e2284980a6517
Merge "Fix submodule fetching in trebuchet" into production