Ruby 1.9.2-rc1: instance_eval can't handle a lambda (needs a proc)

gistfile1.rb

class InstanceEval
  def initialize(code)
    @code = code
    @context = Object.new
  end

  def run
    code = @code
    result = @context.instance_eval(&code)
    "* run --> #{result.inspect}"
  end
end

p = proc { :p }
l = lambda { :l }

puts InstanceEval.new(p).run
puts InstanceEval.new(l).run



# The output in 1.8.7-p72 and in 1.9.1-p378:
# 
#   * run --> :p
#   * run --> :l
# 
# The output in 1.9.2-rc1:
# 
#   * run --> :p
#   code.rb:15:... wrong number of arguments (1 for 0) (ArgumentError)
#           from code.rb:10:in `instance_eval'

@marick, the reason is not known. Ruby 1.8.7 just does it (see example output above).