'attr' implementation is incompatible with MRI 1.9.1 behavior

• Patch Submitted:

  Yes

MRI 1.8's Module#attr method has the following signature:

Module#attr(symbol_name, writable = false)

In MRI 1.9.1, this has been changed to:

Module#attr(symbol_name, ...)

1.9.1 allows one to define multiple attributes with #attr, all writable:

attr :foo, :bar, :baz

JRuby still implements the old 1.8 behavior, even when in 1.9 mode. This prevents irb from starting.

The attached patch fixes this problem.