Hi,
I used dokku-update and was a little bit confused that dokku-apt uses the old application image.

How I have recognized that? I saw the following message while dokku-update has rebuild my app:

-----> Compatible extended app image found, skipping system package installation

I updated from

• dokku:0.29.4 to dokku:0.30.2
• herokuish:0.5.40 to herokuish:0.5.41

My apt-packages file didn't change and it seems that dokku-apt only considers it's own files for the CONTENT_SHA.

• dokku-apt/builder-create-dokku-image

  Line 27 in 3d611d3

  if [[ "$("$DOCKER_BIN" images --quiet "dokku/$APP:$CONTENT_SHA" 2>/dev/null)" != "" ]]; then

• dokku-apt/internal-functions

  Line 22 in 236a972

  fn-apt-fetch-sha() {

Is it on purpose, that I have to use docker to delete the cache image manually... or can you suggest a better solution for that issue?