* vm_insnhelper.c (vm_throw_start): search the target to break
  from a block with nested rescue, from the nested blocks.
  [ruby-core:67765] [Bug #10775] [Fix GH-820]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49390 b2dd03c8-39d4-4d8f-98ff-823fe69b080e