I know there are many questions "LF will be replaced by CRL" but I believe my question is unique as I'm attempting to force LF line-endings, even on Windows, so don't want autocrlf=true.
To force the LF I created a .gitattributes in the root of my repostory with a line:
Doh! .gitattributes line should have been
The warnings can be suppressed using:
git config --global core.safecrlf false