sequence end time is before a component's end time

In a sequence `seq=foo->foo2`, i have seen cases where foo2.start = seq.end, which leads to a case where the interval bracketed by the enclosing sequence does not contain the interval bracketed by the last component; e.g.

seq: 3ac012b39f4e499b8e3db00432be7808
foo2: 71079a13cf6d482f86b681190a66f902

```
|-------- seq ------------- |
|--- foo --| |-- foo2 --|
```