writeDirtyManifestToStream

    fn writeDirtyManifestToStream(self: *Manifest, fw: *Io.File.Writer) !void {
        try fw.interface.writeAll(manifest_header ++ "\n");
        for (self.files.keys()) |file| {
            try fw.interface.print("{d} {d} {d} {x} {d} {s}\n", .{
                file.stat.size,
                file.stat.inode,
                file.stat.mtime,
                &file.bin_digest,
                file.prefixed_path.prefix,
                file.prefixed_path.sub_path,
            });
        }
        try fw.end();
    }