Install setuptools-git on the slaves.

setuptools-git is used by setup_requires, which gets invoked before
virtualenvs are built. Install the package on the slaves to avoid the
distutils easy_install network hit.

Change-Id: I0fd087937bca4f157b1fb0ce29305e369bc8a6b6

modules/jenkins_slave/manifests/init.pp

@@ -80,6 +80,12 @@ class jenkins_slave($ssh_key, $sudo = false, $bare = false, $user = true) {
       ensure => present,
     }
 
+    package { "setuptools-git":
+      ensure => latest,  # okay to use latest for pip
+      provider => pip,
+      require => Package[python-pip],
+    }
+
     package { "git-review":
       ensure => latest,  # okay to use latest for pip
       provider => pip,