Note: while the use-case described is about using submodules within a project, the same applies to a normal git clone of a repository over HTTP.
I have
As this was answered by many but This is just for Winodws USER who is behind proxy with auth.
Re-Installing(first failed, Don't remove).
Goto ->
**Windows**
1. msysgit\installer-tmp\etc\gitconfig
Under [http]
proxy = http://user:pass@url:port
**Linux**
1. msysgit\installer-tmp\setup-msysgit.sh
export HTTP_PROXY="http://USER:PASS@proxy.abc.com:8080"
if you have any special char in user/pass use url_encode