An issue I have with these git driven deployment process (not your specifically which looks well thought-out) is that your are starting from source each time.
I like my deployment across environments to use the exact same binaries that have been validated. Is it just me that is afraid of introducing issues by not doing that ?
Long shot, but you might be interested in http://repeatr.io/ -- it's a tool for our brave-new-container-world intended to make it easy (or at least easier) to suss out reproducible builds.
Or to answer your direct question: "no", it's definitely not just you who's afraid of that :)
I like my deployment across environments to use the exact same binaries that have been validated. Is it just me that is afraid of introducing issues by not doing that ?