Squashed 'sequence/' changes from 0d721a6..2691bee

2691bee version 0.5.3
a373739 merge from master
9fc9a31 bugfix: using the same ExitSequence exception in take and is_empty cannot work
a193c54 added a regression test

git-subtree-dir: sequence
git-subtree-split: 2691bee2f68b7c27a1d1360999d0c21026f77ca9
Merge commit '8bb78ab0d6bf95eea46d0cdedd8462525f2e1f7d' for sequence (fix bug)