Dear Maintainer,
* What led up to the situation?
Checking for defects with
[test-][g|n]roff -mandoc -t -K utf8 -ww -b -z <man page>
[test-groff is a script in the repository for "groff"]
* What was the outcome of this action?
troff: backtrace: '/home/bg/git/groff/build/s-tmac/an.tmac':562: macro 'B'
troff: backtrace: file '<stdin>':97
troff:<stdin>:97: warning: ignoring escape character before '+'
* What outcome did you expect instead?
No output (warnings).
-.-
Remarks and a patch are in the attachments.