Version 5.3.8rc1

The purpose of this pre-release series is to make it easier to test and tune @nsmith-'s read coalescing algorithm in a large test environment.

New features

• feat: Implement read coalescing algorithm by @nsmith- in #1198

Bug-fixes and performance

(none!)

Other

• test: reinstate 'deflate', now that it works on MacOS by @jpivarski in #1206

Full Changelog: v5.3.7...v5.3.8rc1