module RSpec::Support::RubyFeatures

def fork_supported?

this special case.
When we drop support for JRuby 1.7 and/or Ruby 1.8, we can drop

NotImplementedError: fork is not available on this platform
but when you try to fork, it raises an error:
On JRuby 1.7 `--1.8` mode, `Process.respond_to?(:fork)` returns true, 
def fork_supported?
  false
end