Cache never cleaned

Entries in the cache managed by Chisel (storing, among other things, files from the archive) never expire. On a developer machine, this cache can grow over 10Go over time. This can also become problematic in the context of a CI building environment sharing the cache to build multiple images.

Currently the cache can be manually and safely cleaned between chisel executions. But doing so while retaining the advantages of the cache might be uneasy and be burden.

Automatically cleaning old entries in the cache could be a nice UX improvement.