This is running on Ubuntu 12.04, using the most recent versions as of 2013-02-02.
Install git:
$ wget http://git-core.googlecode.com/files/git-1.8.1.2.tar.gz
$ tar xf git-1.8.1.2.tar.gz
$ cd git-1.8.1.2/
$ sudo apt-get install libcurl4-gnutls-dev libexpat1-dev gettext libz-dev
$ make prefix=/usr/local all
$ sudo make prefix=/usr/local install
Install the manpages:
$ wget http://git-core.googlecode.com/files/git-manpages-1.8.1.2.tar.gz
$ sudo tar xf git-manpages-1.8.1.2.tar.gz -C /usr/local/man