pr.md

Locate the section for your github remote in the .git/config file. It looks like this:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = git@github.com:joyent/node.git

Now add a new remote. Obviously, change the github url to match your project's URL. It ends up looking like this:

[remote "github"]
    url = git@github.com:gisce/erp.git
    fetch = +refs/pull/*/head:refs/remotes/github/pr/*

Now fetch all the pull requests:

$ git fetch github
From github.com:gisce/erp
 * [new ref]         refs/pull/1000/head -> github/pr/1000
 * [new ref]         refs/pull/1002/head -> github/pr/1002
 * [new ref]         refs/pull/1004/head -> github/pr/1004
 * [new ref]         refs/pull/1009/head -> github/pr/1009
...

To merge a particular pull request into developer:

$ git checkout developer
$ git merge github/pr/1000