Comment #11 on issue 2783 by [email protected]: wrong placement of
timesignature
http://code.google.com/p/lilypond/issues/detail?id=2783
The former code was in place for ten years, making LilyPond center the
TimeSignature on staff-position 0 for staves with odd line-count, and on
position 1 for staves with even line-count.
My copy of Ted Ross' book on music notation does differently, centering the
time signature on staves with unusual line-count (like percussion staves)
or for modern music moving the time signature clear above the staff.
It seems everyone can get what they want with the override David suggested
\override Staff.TimeSignature #'Y-offset = 2
Other people in addition to Gagi have probably used LilyPond with staves
with unusual line-positions, and somehow got the Time Signature where they
like it, and will upgrade to 2.16.x. It would be difficult to communicate
to them the need to change Y-offset, so wiser to restore the old behavior.
This is just the usual thing to do when an attempted improvement to
software causes an unforeseen change in a formerly-successful application
of the software.