I created very simple git pre-commit hook - that checks for "nocheckin" sequence in staged changes and blocks the commit if it's found.
Most of my time was spent googling git nonsense so I decided to share this.
I'm no git wizard so there may be use case that bypasses my implementation - it works for me with stage (git add) & commit workflow.
https://github.com/fda0/git_nocheckin_hook
It is written in C+stdlib. There are win64 and linux64 binaries on releases page.