I may be crazy, but were you always able to open the door from the lower sewer section (The one you get to through the entrance next to the topside shop building) from the side where the gatekeeper is?
I recently downloaded this latest version, and after talking to the gate guy and giving him a pizza, I went straight down to the gate and opened it up from that side, which I thought I needed a key to get.
Nothing bad seemed to happen from opening it without doing the key quest.
Just making sure I didn't encounter a bug.