* What led up to the situation?

     Checking for defects with

test-[g|n]roff -mandoc -t -K utf8 -rF0 -rHY=0 -ww -b -z < "man page"

  [Use "groff -e ' $' <file>" to find trailing spaces.]

  ["test-groff" is a script in the repository for "groff"; is not shipped]
(local copy and "troff" slightly changed by me).

  [The fate of "test-nroff" was decided in groff bug #55941.]

   * What was the outcome of this action?


troff: backtrace: '<stdin>':11: macro 'Vb'
troff: backtrace: file '<stdin>':336
troff:<stdin>:336: warning: font name 'CW' is deprecated
troff: backtrace: file '<stdin>':440
troff:<stdin>:440: warning: [page 5, 9.1i]: cannot break line

Output from "test-nroff  -mandoc -t -K utf8 -rF0 -rHY=0 -ww -b -z ":

troff: backtrace: file '<stdin>':440
troff:<stdin>:440: warning: [page 6, line 27]: cannot break line
troff: backtrace: file '<stdin>':755
troff:<stdin>:755: warning: [page 10, line 41]: cannot break line


   * What outcome did you expect instead?

     No output (no warnings).

-.-

  General remarks and further material, if a diff-file exist, are in the
attachments.