Quantum/plugins/ryu: minor update for Quantum Ryu plugin

- updated package list for Ryu
  ryu plugin/agent needs python-netifaces
- quantum-ryu-agent also needs ryu module

Change-Id: I5b49efceb65e8139a49a8e82f55ea6aa7d1eebac
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
diff --git a/lib/quantum_thirdparty/ryu b/lib/quantum_thirdparty/ryu
index f11951a..5717d82 100644
--- a/lib/quantum_thirdparty/ryu
+++ b/lib/quantum_thirdparty/ryu
@@ -49,8 +49,16 @@
     echo "${RYU_CONF_CONTENTS}" > $RYU_CONF
 }
 
+# install_ryu can be called multiple times as quantum_pluing/ryu may call
+# this function for quantum-ryu-agent
+# Make this function idempotent and avoid cloning same repo many times
+# with RECLONE=yes
+_RYU_INSTALLED=${_RYU_INSTALLED:-False}
 function install_ryu() {
-    git_clone $RYU_REPO $RYU_DIR $RYU_BRANCH
+    if [[ "$_RYU_INSTALLED" == "False" ]]; then
+        git_clone $RYU_REPO $RYU_DIR $RYU_BRANCH
+        _RYU_INSTALLED=True
+    fi
 }
 
 function start_ryu() {