String#encode fails with :invalid => :replace option #375
Description
Under MRI (1.9.3-p286):
dudley@kima ~ :> ruby -e 'puts "foo".encode("UTF-16", :invalid => :replace)'
??foo
Under JRuby (1.7.0):
dudley@kima ~ :> ruby -e '"foo".encode("UTF-16", :invalid => :replace)'
CharsetEncoder.java:285:in `replaceWith': java.lang.IllegalArgumentException: Illegal replacement
from CharsetTranscoder.java:201:in `getCharsetEncoder'
from CharsetTranscoder.java:69:in `transcode'
from CharsetTranscoder.java:58:in `transcode'
from CharsetTranscoder.java:97:in `transcode'
from RubyString.java:7559:in `transcode'
from RubyString.java:7525:in `encode'
from RubyString$INVOKER$i$encode.gen:-1:in `call'
from MethodHandle.java:599:in `invokeWithArguments'
from InvocationLinker.java:183:in `invocationFallback'
from -e:1:in `__file__'
from -e:-1:in `load'
from Ruby.java:770:in `runScript'
from Ruby.java:763:in `runScript'
from Ruby.java:640:in `runNormally'
from Ruby.java:489:in `runFromMain'
from Main.java:375:in `doRunFromMain'
from Main.java:264:in `internalRun'
from Main.java:230:in `run'
from Main.java:214:in `run'
from Main.java:194:in `main'
According to the docs (http://www.ruby-doc.org/core-1.9.3/String.html#method-i-encode), the replacement string should default to "\uFFFD" for Unicode encoding forms, and "?" otherwise.