A lot of us have been reading the new Necron codex for any signs of 6th edition material and insight. Here is one of these little bits of insight, or perhaps it comes down to a glaring error in the proof reading department.
One of the upgrades for the Canoptek Spyders says it can repair vehicles unless it has gone to ground. But MC's aren't allowed to GtG... so maybe a rule change in 6th?
Following is a reasonable explanation from 6th edition rumors regarding Bracing in 6th edition.
In the 6th ed rumours there is a Brace rule:
who: tanks, walkers, monstrous creatures
when: being shot at, before rolls are made
instant effect: one weapon destroyed ignored, two saves for MC like IC
lasting effect: Suppressed, if not already Suppressed