Detached head during image building

[parserpro]

Running

docker build -t caffe:cpu https://raw.githubusercontent.com/BVLC/caffe/master/docker/cpu/Dockerfile

get

`Step 7/12 : RUN git clone -b ${CLONE_TAG} --depth 1 https://github.com/BVLC/caffe.git . && pip install --upgrade pip && cd python && for req in $(cat requirements.txt) pydot; do pip install $req; done && cd .. && mkdir build && cd build && cmake -DCPU_ONLY=1 .. && make -j"$(nproc)"
---> Running in 0a91bffbd189
Cloning into '.'...
Note: checking out 'eeebdab16155d34ff8f5f42137da7df4d1c7eab0'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

git checkout -b
`