Repro:
git init temp-repo && cd temp-repo && echo foo > "foo file" && git add "foo file" && git commit -m foo && git mv "foo file" "bar file" && git commit -m "rename foo to bar" && git fast-export -C -M HEAD | grep ^R
Outputs:
R foo file bar file
It should output:
R "foo file" "bar file"
This was allegedly fixed by 6280dfdc3b (fast-export: quote paths in output, 2011-08-05). It seems that that commit expects quote_c_style to output surrounded quotes when the path contains spaces, but both empirically and from my quick look at quote_c_style, it doesn't seem that the function does that.
Sadly, I don't have time to submit a fix ATM.
j.