Bug#620185: M-q problem in changelog mode

[Xiyue Deng]

Control: tags 620185 + pending

FYI a potential fix is applied[1] and will be shipped with the next
release.

[1] 
https://salsa.debian.org/emacsen-team/dpkg-dev-el/-/commit/d9cb4cce57d2c887bdb9e74c97b0f8951cbd8b1b