add Fedora x86_64 image for nodepool

Change-Id: I54fdc81e2a233fdcf90534aff6be7984e28f6133
diff --git a/tools/image_list.sh b/tools/image_list.sh
index fa6b92e..f9a4e2f 100755
--- a/tools/image_list.sh
+++ b/tools/image_list.sh
@@ -12,6 +12,7 @@
 # Extra variables to trigger getting additional images.
 ENABLED_SERVICES=h-api
 HEAT_FETCHED_TEST_IMAGE="Fedora-i386-20-20131211.1-sda"
+PRECACHE_IMAGES=True
 
 # Loop over all the virt drivers and collect all the possible images
 ALL_IMAGES=""