IRRd 4.0.1 fixes a bug in object deletion[1] and upgrades
the twisted version to 19.2.1 to ensure CVE-2019-12387 is
fixed.
The bug in object deletion prevented the deletion of
objects with no inbound references, such as certain route
objects. CVE-2019-12387 likely did not affect IRRd, as it
affected components of twisted that are not directly used
in IRRd, but upgrading is recommended to be sure.
IRRd 4.0.1 is entirely backwards compatible with 4.0.0.
[1] #228