weird output from git ls-files on travis

[7yl4r]

Not sure why git-ls does this, but these first few lines are breaking the builds:

$ git ls-files -m -o -X .gitignore -x '*.html' | xargs ls -lh
ls: cannot access examples/robis_files/figure-gfm/bathymetry: No such file or directory
ls: cannot access from: No such file or directory
ls: cannot access marmap-1.png: No such file or directory
ls: cannot access examples/robis_files/figure-gfm/ggplot2: No such file or directory
ls: cannot access histograms-1.png: No such file or directory
ls: cannot access examples/robis_files/figure-gfm/ggplot2: No such file or directory
ls: cannot access histograms-2.png: No such file or directory
ls: cannot access examples/robis_files/figure-gfm/more: No such file or directory
ls: cannot access advanced: No such file or directory
ls: cannot access Spio: No such file or directory
ls: cannot access example-1.png: No such file or directory
-rw-rw-r-- 1 travis travis  884 Dec  6 22:59 examples/images.md
-rw-rw-r-- 1 travis travis  404 Dec  6 22:59 examples/index.md
-rw-rw-r-- 1 travis travis  26K Dec  6 22:59 examples/ioos_portal_data_view_files/figure-gfm/histograms-1.png
...

git ls-files is returning files that don't exist? Seems weird, not sure what could cause this, can't reproduce locally.