Ruby » Ruby master

merge revision(s) 55181: [Backport #12431]

    * transcode.c (str_transcode0): scrub in the given encoding when
      the source encoding is given, not in the encoding of the
      receiver.  [ruby-core:75732] [Bug #12431]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@55936 b2dd03c8-39d4-4d8f-98ff-823fe69b080e