When vaulting into all supermarket, the character does not stand on the building floor, instead stands on the terrain ground. Going prone allows you to move around the supermarket unseen, you can still loot, and can still pop up out of the floor and fire/attack by going crouch. You can then move back into prone (and thus out of sight). You can also exit the supermarket on terrain level, with no harm to character.
Zombies also always glitch into supermarket, so you can only ever see their upper torso.
Applies to all versions, including current build 0.30.113860
Please sort this issue before it is used as an exploit. {F28781} {F28782} {F28783} {F28784} {F28785} {F28786}