brew installation error : Appears homebrew is already installed

brew installation error : Appears homebrew is already installed

unknown7cd1c37eb7ca:local shoaibali$ ruby -e "$(curl -fsSL
https://raw.github.com/mxcl/homebrew/go)"
-e:67: warning: Insecure world writable dir /usr/local/bin in PATH, mode
040777
-e:96: warning: Insecure world writable dir /usr/local/bin in PATH, mode
040777
It appears Homebrew is already installed. If your intent is to reinstall you
should do the following before running this installer again:
rm -rf /usr/local/Cellar /usr/local/.git && brew cleanup
unknown7cd1c37eb7ca:local shoaibali$ ls
CONTRIBUTING.md foreman hw_mp_userdata
Library git libexec
PortDetect.log heroku opt
bin hw_mobile_userdata share
unknown7cd1c37eb7ca:local shoaibali$
Hey guys, I was having some problems with my brew when I was trying to
install ffmpeg. I think I did the immature thing (note - after hours of
trying) of uninstalling brew (through some article i read online) and
trying to reinstall it. But the above output comes in my terminal when I
try to install brew again. How can it say Homebrew is already installed
when clearly the Cellar file isn't there ?