__FILE__ in a binding gets overwritten

[banister]

When using binding.eval(code, my_file) the my_file seems to overwrite the actual __FILE__ for the binding causing subsequent calls to binding.eval("__FILE__") to return my_file.

MRI (desired) behaviour:

> b.eval("__FILE__")
=> "(pry)"
> b.eval(":hello", "pig.rb")
=> :hello
> b.eval("__FILE__")
=> "(pry)"

Rubinius behaviour:

> b.eval("__FILE__")
=> "(pry)"
> b.eval(":hello", "pig.rb")
=> :hello
> b.eval("__FILE__")
=> "pig.rb"