Use a new image name each time we snapshot.

Work around a bug in RS cloud servers where after deleting an image,
you may not be able to create a new one with the same name.  Instead,
generate a unique name for every image, and when we go to use it, find
an image that _starts_ with the name we're looking for.

Change-Id: I2e674c544b96e976c0460298ab74de1da8e7144c

slave_scripts/devstack-vm-launch.py

@@ -52,7 +52,10 @@ if CLOUD_SERVERS_DRIVER == 'rackspace':
     sizes = [sz for sz in conn.list_sizes() if sz.ram >= MIN_RAM]
     sizes.sort(lambda a,b: cmp(a.ram, b.ram))
     size = sizes[0]
-    image = [img for img in conn.list_images() if img.name==IMAGE_NAME][0]
+    images = [img for img in conn.list_images() 
+              if img.name.startswith(IMAGE_NAME)]
+    images.sort()
+    image = images[-1]
 else:
     raise Exception ("Driver not supported")
 

slave_scripts/devstack-vm-update-image.py

@@ -50,11 +50,8 @@ if CLOUD_SERVERS_DRIVER == 'rackspace':
     node = [n for n in conn.list_nodes() if n.name==SERVER_NAME][0]
 
     print "Searching for %s image" % IMAGE_NAME
-    image = [img for img in conn.list_images() if img.name==IMAGE_NAME]
-    if image: 
-        image = image[0]
-    else: 
-        image = None
+    images = [img for img in conn.list_images() 
+              if img.name.startswith(IMAGE_NAME)]
 else:
     raise Exception ("Driver not supported")
 
@@ -81,9 +78,11 @@ run('run puppet', 'sudo bash -c "cd /root/openstack-ci-puppet && /usr/bin/git pu
 run('stop mysql', 'sudo /etc/init.d/mysql stop')
 run('stop rabbitmq', 'sudo /etc/init.d/rabbitmq-server stop')
 
-if image:
+for image in images:
     conn.ex_delete_image(image)
 
+IMAGE_NAME = IMAGE_NAME+'-'+str(int(time.time()))
+
 image = conn.ex_save_image(node=node, name=IMAGE_NAME)
 
 last_extra = None