libreoffice4 coredump / Xcursor mystery

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

On a yesterday's -current/amd64 and pkgsrc box, soffice didn't start,
as in, the splash screen appeared, the bar didn't move, and one was
eventually returned to the prompt. Luckily it left a coredump
behind:

#0  0x00007f7fd2875a10 in _X11TransWritev () from /usr/X11R7/lib/libX11.so.6
#1  0x00007f7fd28744c9 in _XSend () from /usr/X11R7/lib/libX11.so.6
#2  0x00007f7fd286ad0f in XQueryExtension () from /usr/X11R7/lib/libX11.so.6
#3  0x00007f7fd286ab84 in XInitExtension () from /usr/X11R7/lib/libX11.so.6
#4  0x00007f7fd2c06b52 in XRenderFindDisplay ()
   from /usr/X11R7/lib/libXrender.so.1
#5  0x00007f7fd2c07979 in XRenderQueryExtension ()
   from /usr/X11R7/lib/libXrender.so.1
#6  0x00007f7fd2e06f44 in _XcursorGetDisplayInfo ()
   from /usr/X11R7/lib/libXcursor.so.1
#7  0x00007f7fd2e07529 in XcursorSupportsARGB ()
   from /usr/X11R7/lib/libXcursor.so.1
#8  0x00007f7fd2e02cc3 in XcursorNoticeCreateBitmap ()
   from /usr/X11R7/lib/libXcursor.so.1
#9  0x00007f7fdba40435 in XCreatePixmap () from /usr/X11R7/lib/libX11.so.7
#10 0x00007f7fd92319d7 in SalDisplay::initScreen(SalX11Screen) const ()
   from /usr/pkg/libreoffice4-4.2.4.2/program/libvclplug_genlo.so

So the shared library mystery is why the ancient libXcursor.so.1 is used
instead of libXcursor.so.2, given that libreoffice calls into the new
libX11.so.7.

Stranger still: the libreoffice4 was installed from a binary package built
on a -current box which doesn't have libX11.so.6 nor libXcursor.1, so there
can't be any references to them from the libreoffice4 side.

The workaround was just to delete libXcursor.so.1*

Any thoughts on what happened?

Cheers,

Patrick