Unreleased Changes in The Mainline

Breaking Changes

DKIM signer TTLs can be now be expressed using duration strings like "5 mins". Previously you could only use the integer number of seconds.
debian packages will now unmask kumod and tsa-daemon services as part of post installation. Thanks to @cai-n! #331
memoize now has an optional invalidate_with_epoch parameter that allows you to opt a specific cache into epoch-based invalidation.
DKIM signer has a separate supplemental cache for the parsed key data, which helps to reduce latency for deployments where the same key data is shared between multiple signing domains.
New msg:shrink() and msg:shrink_data() methods.
Added various python compatibility functions to the minijinja template engine. See the pycompat docs for a list of the additional functions.
New kumo.string.eval_template function for expanding minijinja template strings.
New low_memory_reduction_policy, no_memory_reduction_policy and options give advanced control over memory vs. spool IO trade-offs when available is memory low.
New shrink_policy option to give advanced control over memory vs. spool IO trade-offs when messages are delayed.

When using kumo.dkim.set_signing_threads, some extraneous unused threads would be created.
Using a display name with commas in the builder mode of the HTTP injection API would produce an invalid mailbox header.