sigil.wad breaks normal access to Episodes 2, 3 and 4 of Ultimate Doom

[robwill80]

Using the standard version of sigil.wad (not the "compat" version) as a way of also playing regular episodes of Ultimate Doom doesn't work. Trying to start "The Shores of Hell," "Inferno," or "Thy Flesh Consumed" will all take the player to the start of "Knee-Deep in the Dead" - E1M1: Hangar.