I originally had a symlink "thrift" that was linked to another file in the same directory.
In my diff, I replaced the symlink with a normal file. arc patch failed while handling this case.
[test-go-build] $ git reset --hard 0fb803220fdbd898b9ffabb34155811744d81f75 HEAD is now at 0fb8032 [...] [test-go-build] $ git clean -fd -f [test-go-build] $ git submodule update --init --recursive [test-go-build] $ arc patch --diff 1357218 --nocommit --nobranch ******** Checking patch dev/null => thrift... error: dev/null: does not exist in index Patch Failed!