Infinite Dungeon: Inaccessible vault

[Sirioh]

http://i.imgur.com/nCUXPpC.png

I have dug out all possible walls adjacent to this vault, but no doors exist. The only walls that remain are those that border another vault to the south. Presumably the vault is oriented in such a way that the door is adjacent to the southern vault, but because I cannot dig through that vault's walls, the door is inaccessible.

For disclosure, I am running EverythingIsUnique, ID500, IDVariety, IDAlchemy, and Zomnibus. However, I think it is likely this relates to vanilla ID generation since of those, the only one that affects ID level generation at all is ID500, and that only by allowing minor side zones, like drake and rogue caves, to spawn in the ID. IDVariety doesn't affect level generation at all beyond cosmetically allowing alternate tile sets (but this could perhaps have caused it too).

I did try digging each of the vault's external walls themselves, in case this was a new vault that I was not familiar with that had no door, but predictably this was unsuccessful.

Presumably, the easiest solution to avoid this in the future would be to force a ring of floor tiles around any vault. More complex methods might be to check accessibility of doors and re-orient the vault if the three tiles adjacent to the door are non-diggable, or enforce a minimum distance between vaults.