Cloning this repository:

git clone git://gitorious.org/android-on-freerunner/platform_external_zlib.git platform_external_zlib
cd platform_external_zlib

Add this repository as a remote to an existing local repository:

git remote add platform_external_zlib git://gitorious.org/android-on-freerunner/platform_external_zlib.git
git fetch platform_external_zlib
git checkout -b my-local-tracking-branch platform_external_zlib/master_or_other_branch