c.Assert(err, check.IsNil)
c.Check(tseq, check.DeepEquals, tileSeq{"test-seq": []tileLibRef{{0, 1}, {1, 1}, {2, 1}}})
// tags appear in seq: 0, 1, 3, 0, 4 -> skip second tag0
c.Assert(err, check.IsNil)
c.Check(tseq, check.DeepEquals, tileSeq{"test-seq": []tileLibRef{{0, 1}, {1, 1}, {2, 1}}})
// tags appear in seq: 0, 1, 3, 0, 4 -> skip second tag0