Incoming emails may cause "invalid byte sequence" error depending on the default external encoding, due to r18317 (#31549).

git-svn-id: http://svn.redmine.org/redmine/trunk@18544 e93f8b46-1217-0410-a6f0-8f06a7374b81

extra/mail_handler/rdm-mailhandler.rb

@@ -212,4 +212,4 @@ END_DESC
 end
 
 handler = RedmineMailHandler.new
-exit(handler.submit(STDIN.read))
+exit(handler.submit(STDIN.read.force_encoding('ASCII-8BIT')))