<!-- One change per pull request. docs/CONTRIBUTING.md says what gets in. -->

**The issue it fixes** (`Fixes #N`, if there is one)

**What this changes**

**What 1.12.1 does, and how you know** (the client's behaviour, a DBC field, a FrameXML line, a capture)

**How you checked it** (`scripts/check.sh` or `scripts/gates.sh`, and before and after)