Add missing helper

hooks/charmhelpers/contrib/openstack/alternatives.py

@@ -0,0 +1,17 @@
+''' Helper for managing alternatives for file conflict resolution '''
+
+import subprocess
+import shutil
+import os
+
+
+def install_alternative(name, target, source, priority=50):
+    ''' Install alternative configuration '''
+    if (os.path.exists(target) and not os.path.islink(target)):
+        # Move existing file/directory away before installing
+        shutil.move(target, '{}.bak'.format(target))
+    cmd = [
+        'update-alternatives', '--force', '--install',
+        target, name, source, str(priority)
+    ]
+    subprocess.check_call(cmd)