[Bug #1963] redo'ing deadlock causes [BUG]

Bug #1963: redo’ing deadlock causes [BUG]
http://redmine.ruby-lang.org/issues/show/1963

e$B5/I<<Te(B: Usaku NAKAMURA
e$B%9%F!<%?%9e(B: Open, e$BM%@hEYe(B: Normal
e$B%+%F%4%je(B: core, Target version: 1.9.x
ruby -v: ruby 1.9.2dev (2009-08-20 trunk 24594) [i386-mswin32]

#1951
e$B$K4X78$,$"$k$h$&$J$J$$$h$&$JOC$G$9$,!“0J2<$N%9%/%j%W%H$,e(B[BUG]e$B$GMn$A$^$9!#e(B
e$B%W%i%C%H%U%)!<%`0MB8$O$”$j$^$;$s!#e(B

th = Thread.new{ Thread.stop }
1.times do
begin
Thread.stop
ensure
redo
end
end

e$B%A%1%C%He(B #1963 e$B$,99?7$5$l$^$7$?!#e(B (by Yusuke E.)

e$B%9%F!<%?%9e(B Opene$B$+$ie(BClosede$B$KJQ99e(B
e$B?JD=e(B % 0e$B$+$ie(B100e$B$KJQ99e(B

Applied in changeset r24616.

http://redmine.ruby-lang.org/issues/show/1963