```
Not done as a scripted diff to avoid misnaming the local variable in
ProcessMessage().
```
Partial backport of [[ https://github.com/bitcoin/bitcoin/pull/19829 | core#19829 ]]:
https://github.com/bitcoin/bitcoin/pull/19829/commits/78040f91687e7f1986e466d448c9b9530830e9b8
Depends on D10866.
Ref T1696.