When trying to clone a large git repository (about 2.5GB) the git clone command fails with

RPC failed; result=22, HTTP code = 500

The git repository is served via http (ssh is not possible because of the required 6.2 version of sshd)

The server is running Ubuntu 12.04 LTS with Apache2 and PHP 5.3.10. The error logged is:

[Sat Apr 12 16:28:45 2014] [error] [client 192.168.88.134] PHP Fatal error:  String size overflow in /home/git/phabricator/libphutil/src/future/exec/ExecFuture.php on line 712