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**API**
- Batch endpoint now checks for and aborts any parent request if subrequest encounters 409 constraint violation (fixes 1569)
**Bug fixes**
- Fix a bug where you could not reach the last records via Next-Header when deleting with pagination (fixes 1170)
- Slight optimizations on the ``get_all`` query in the Postgres
storage backend which should make it faster for result sets that
have a lot of records (1622). This is the first change meant to
address 1507, though more can still be done.
- Fix a bug where the batch route accepted all content-types (fixes 1529)
**Internal changes**
- Upgrage to kinto-admin v1.17.1