Wrong argument type String (expected Data) (TypeError) on 1.8 with dl

1.8 e$B$G$H$-$*$je(B RubySpec e$B$,Mn$A$k$N$G!"e(B
http://www.rubyist.net/~akr/chkbuild/debian/ruby-1.8/log/20081227T205959.txt.gz
e$B$A$g$C$H$$F$$?$ie(B DL e$B$r;H$C$F$^$7$?!#e(B

e$B:F8=$G$-$k$+;n$7$?$H$3$m!“$H$j$”$($:0J2<$N$h$&$K$9$k$He(B
-e:7:in `[]': wrong argument type String (expected Data) (TypeError)
e$B$H$$$&%(%i!<$,=P$k$h$&$G$9!#e(B

% ./ruby -rdl -ve ’
GC.stress = true
10.times {
ptr = [“ABC”].pack(“p”)
addr = ptr.unpack(“L”).first
dptr = DL::PtrData.new(addr, 1)
p dptr[0,1]
}

ruby 1.8.7 (2008-12-21 revision 20895) [i686-linux]
“A”
-e:7:in []': wrong argument type String (expected Data) (TypeError) from -e:7 from -e:3:in times’
from -e:3