I noticed that the X11 contrib mirrors listed in bsd.pkg.mk are not
necessarily in sync with ftp.x.org (the particular cases I noticed are
described in updates I submitted to xfig and transfig in PR's 13324 and
13325).  I checked on www.x.org (which, unlike to ftp.x.org, is up), and
they have a nice list of worldwide X11 mirrors at:

  http://www.x.org/download.htm

Now, probably not all of these are up to date, and they may not all carry
contrib sources.  I see that neither of the mirrors listed in
MASTER_SITE_XCONTRIB is on the list.  I've checked a few of them, and
the following had up to date versions of xfig and transfig (thus, presumably
other sources):

  ftp://uiarchive.uiuc.edu/pub/ftp/ftp.x.org/contrib/
  ftp://ftp.ntua.gr/pub/X11/contrib/
  ftp://sunsite.icm.edu.pl/pub/X11/contrib/
  ftp://sunsite.doc.ic.ac.uk/packages/X11/contrib/

There are many more that I didn't check, since distant servers tend to
take a long time to check (the last three above tried my patience a bit).
Maybe it would be a good idea to change the MASTER_SITE_XCONTRIB list in
bsd.pkg.mk.

--Jim