one = alloc_filespec(old_name);
two = alloc_filespec(new_name);
fill_filespec(one, old_sha1, old_mode);
fill_filespec(two, new_sha1, new_mode);
one = alloc_filespec(old_name);
two = alloc_filespec(new_name);
fill_filespec(one, old_sha1, old_mode);
fill_filespec(two, new_sha1, new_mode);