RUN Layers are not being cached properly

[UmairShahid95]

Actual behavior
The following directive:

RUN apt-get update -y &&
apt-get install -y postgresql-client

gets cached but the cache is not used in the subsequent runs
--cache=true is activated

Expected behavior

it should be cached properly and cache should be utilized in subsequent runs

[anselms]

Same issue here. For

RUN apt-get update && apt-get install --assume-yes --no-install-recommends \
    nginx tini libpango-1.0-0 libpangoft2-1.0-0 && \
    rm -rf /var/cache/apt/archives/*

the cache is never used.

[anselms]

BTW, this does not seem to share the root cause with #3246, as we observe this caching problem without using WORKDIR in our Dockerfile (and neither is WORKDIR used in the base image)