I thought at first it was merely a gas trick but something was different.
SCV is walking through buildings! and his super-stacked SCVs just sat on my cc and started attacking it.
After the game, I watched a replay and saw SCV walked through the water and high grounds.
He made collision-check-free SCV one by one by doing something to the SCV building a supply depot.
Is this a new glitch?
Here is a replay
EDIT: here is a youtube link