* 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: file '<stdin>':81
troff:<stdin>:81: warning: trailing space in the line
troff: backtrace: file '<stdin>':86
troff:<stdin>:86: warning: trailing space in the line
troff: backtrace: file '<stdin>':108
troff:<stdin>:108: warning: trailing space in the line

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

troff: backtrace: file '<stdin>':81
troff:<stdin>:81: warning: trailing space in the line
troff: backtrace: file '<stdin>':86
troff:<stdin>:86: warning: trailing space in the line
troff: backtrace: file '<stdin>':108
troff:<stdin>:108: warning: trailing space in the 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.