Save the ~/docker directory in cache because rebuild_image stores things there

circle.yml

@@ -14,6 +14,8 @@ machine:
     CLOUDSDK_CORE_DISABLE_PROMPTS: 1
 
 dependencies:
+  cache_directories:
+    - "~/docker"
   post:
     - "sudo apt-get update && sudo apt-get install bc jq"
     - curl https://sdk.cloud.google.com | bash