building what's in pwd vs building what is identified by a hash id - benclifford/text GitHub Wiki

(hash id might be a git commit ID or a docker container ID)

in the former we need to start from scratch when building a new checkout because we don't have any context. then further changes are made against that context. doesn't work so well for building multiple branches alternately in the same workspace because we only have a "latest" build that is implicitly identified by being in the pwd.