Unable to build Ruby bindings on OS X

I'm unable to build the SWIG/Ruby bindings on Mac OS X:

$ make swig-rb
/opt/local/bin/swig -I/Users/dlr/src/subversion/subversion/include -I/Users/dlr/src/subversion/subversion/bindings/swig -I/Users/dlr/src/subversion/subversion/bindings/swig/include -I/Users/dlr/src/subversion/subversion/bindings/swig/proxy -I/Users/dlr/src/subversion/subversion/bindings/swig/proxy -I/opt/local/include/apr-1 -I/opt/local/include/apr-1 -I/opt/local/include -ruby -o subversion/bindings/swig/ruby/svn_client.c ./subversion/bindings/swig/svn_client.i
/bin/sh /Users/dlr/src/subversion/libtool --tag=CC --silent --mode=compile none -DDARWIN -DSIGPROCMASK_SETS_THREAD_MASK -no-cpp-precomp -I/opt/local/include/apr-1 -I/opt/local/include/apr-1 -I/opt/local/include -I/Users/dlr/src/subversion/subversion/bindings/swig/ruby/libsvn_swig_ruby -prefer-pic -c -o subversion/bindings/swig/ruby/svn_client.lo subversion/bindings/swig/ruby/svn_client.c
/Users/dlr/src/subversion/libtool: line 1: none: command not found
make: *** [subversion/bindings/swig/ruby/svn_client.lo] Error 1

This failure is due to my libtool. Here's snippet from ktrace, where I see
it searching through all the paths in my $PATH env var:

26211 sh CALL stat(0x3a89e0,0xbfffbab0)
26211 sh NAMI "/usr/local/subversion/bin/none"
26211 sh RET stat -1 errno 2 No such file or directory

My libtool is littered with references to "none". Here's a few examples:

      # No PIC object so indicate it doesn't exist in the libtool
      # object file.
      test -z "$run" && cat >> ${libobj}T <<EOF
pic_object=none

...

# Name of the non-PIC object.
non_pic_object=none

...

                if test -z "$pic_object" || \
                   test -z "$non_pic_object" ||
                   test "$pic_object" = none && \
                   test "$non_pic_object" = none; then
                  $echo "$modename: cannot find name of object for \`$arg'" 1>&2
                  exit 1
                fi

In this case, libtool doesn't seem to be expecting having the PIC object be
none (though it appears to handle some instances of it). Anyone familiar with
how to fix this problem?

-- 
Daniel Rall