Finally I can reproduce even in the Homebrew version. It will only leak when I use relative path. and all version also can reproduce. b4 I test Homebrew version with full path not relative path that's the different....XD~

map $pid $public_root { default public; } <-- this one relative path leak happened
map $pid $public_root { default /usr/local/Cellar/nginx/1.4.1/public; } <- this one full path without leak..