While creating message, if Content-Type exists and charset is not specified, then treat as us-ascii and don't replace Content-Type.
While creating message, if Content-Type exists and charset is not specified, then treat as us-ascii and don't replace Content-Type.


git-svn-id: 12ae5aeef08fd453d75833463da4cc20df82a94e@2128 8af8166b-12a6-a448-a533-9086ace3f9f6

snakamura/q3,snakamura/q3,snakamura/q3,snakamura/q3,snakamura/q3,snakamura/q3,snakamura/q3,snakamura/q3,snakamura/q3