There have been attempts to address git's shortcomings with respect to independent revision control of a single file: There is the "zit" project at
...although it wasn't ideal for me, and it doesn't look like it's been updated in a while. E.g., these days that should be on GitHub!
RCS really fits well with the use-case of /etc configuration files. It's a pity that Git doesn't function very well for that particular case.