problem with input/regression/page-label.ly

[James Bailey]

As shown in the attached image, the \mark \markup is placed too far  
to the left in 2.13.9. It was fine in 2.12. My question is, how  
should I add this to the tracker? I'm not quite certain under what  
circumstances the mark is so far to the left, and the problem is (I  
think) more with the \mark \markup rather than with the page  
labeling. To that end, I've reduced the problem to the following:
\version "2.12.0"

#(set-default-paper-size "a6")

{
 c'2 c' \mark \markup { A (page 3) }
 \break
  c' c'
}

I include the old version statement, because that's the one in the  
regression test, where this worked, although the problem only shows  
up with the new version.