Actually install the requirements repo.

The requirements repo has had a setup.cfg etc for a long time but only
recently started using it. As it now has dependencies, we need to pip
install it. To preserve compat with older requirements repos I haven't
changed the call to invoke update-requirements yet, as we still have
the update.py symlink.

The pbr install is moved before requirements to ensure we don't
trigger easy-install.

Change-Id: I7d7e91694c9145fac0ddab8a9de5f789d723c641
diff --git a/lib/infra b/lib/infra
index c825b4e..5fb185f 100644
--- a/lib/infra
+++ b/lib/infra
@@ -29,9 +29,6 @@
 
 # install_infra() - Collect source and prepare
 function install_infra {
-    # bring down global requirements
-    git_clone $REQUIREMENTS_REPO $REQUIREMENTS_DIR $REQUIREMENTS_BRANCH
-
     # Install pbr
     if use_library_from_git "pbr"; then
         git_clone_by_name "pbr"
@@ -41,6 +38,10 @@
         # in via system packages.
         pip_install "-U" "pbr"
     fi
+
+    # bring down global requirements
+    git_clone $REQUIREMENTS_REPO $REQUIREMENTS_DIR $REQUIREMENTS_BRANCH
+    pip_install $REQUIREMENTS_DIR
 }
 
 # Restore xtrace