One of the strange things I've encountered is bare \r (i.e. no accompanying \n) in the middle of a line from a windows-sourced file. Don't know how they got there, just that redshift didn't like it one bit.
odd Windows gave you that - believe \r was Mac's standard at one point…
I think how it happens with windows is one windows editor adds \r\n and then the file is edited in an editor that isn't properly aware of the windows line ending and the \n gets deleted. I've seen this happen before. It's especially likely to happen if the file has mixed line endings.