After lighting a large nether portal, not zombie pigmen were spawned in or around the portals. This bug occurred in the highest difficulty, and in survival mode (originally creative)
Steps to reproduce:
Build a 23 wide by 21 tall nether portal, light it, and observe.
Linked issues
Attachments
Comments 11

Sammy - http://minecraft.gamepedia.com/Zombie_pigmen
"Zombie pigmen are capable of spawning on the bottom row of obsidian in a Nether portal frame in the Overworld. Spawning inside a nether portal is a factor of the number of portal blocks in the portal - each block has a chance of spawning a zombie on the base of the portal.[note 1] Building bigger portals means more pigmen spawn, where the smallest 2×3 portal (4×5 frame) has the lowest likelihood of a spawn."
Sammy - http://minecraft.gamepedia.com/Zombie_pigmen
"Zombie pigmen are capable of spawning on the bottom row of obsidian in a Nether portal frame in the Overworld. Spawning inside a nether portal is a factor of the number of portal blocks in the portal - each block has a chance of spawning a zombie on the base of the portal.[note 1] Building bigger portals means more pigmen spawn, where the smallest 2×3 portal (4×5 frame) has the lowest likelihood of a spawn."
Duplicate:MCPE-10839