I suspect it is a line-ending issue - @msteiger hit it too, I believe. Something causes just that one file to get flagged as changed, yet diffs show no change. I tried to tweak the .gitattributes to improve line ending further, thought maybe this one had to be "fixed" by being recommitted (the GitHub line ending doc suggests that) but I even saw it get reflagged after committing :-(

Can't even revert it - if I tried Git would revert it happily yet it would stay flagged. Completely resetting my workspace would make it go away until whatever happened to trigger the change again.

I'd take it out of the commit if I could find an obvious way to do so. I miss Perforce's obliterate :-(