bindings steal globals

gistfile1.rb

# using IRB jruby-1.7.16
sem = Java.javax.script.ScriptEngineManager.new
# => #<Java::JavaxScript::ScriptEngineManager:0x5bb21b69> 
$FOO
# => nil 
$FOO = "1"
# => "1" 
jr = sem.getEngineByName("jruby")
# => #<Java::OrgJrubyEmbedJsr223::JRubyEngine:0x7ce6a65d> 
jr.eval("$FOO")
# => "1" 
$FOO
# => nil #What? it stole the global!
$FOO = "2"
# => "2" 
jr.eval("$FOO")
# => "1" 
jr.setBindings(sem.getBindings, javax.script.ScriptContext.ENGINE_SCOPE)
# => nil 
jr.eval("$FOO")
# => "1" 
$FOO
# => nil # What? It reset the global!
$FOO = "3"
# => "3" 
$FOO
# => "3" 
jr.eval("$FOO")
# => "1"