net/http: Transport should de-UTF-8 hostname in Host header

[bradfitz]

From golang-nuts, a test was failing in Go 1.6 against httptest.Server because of a unit test line:

    {"http://Doppel.Gänger/foo_Bar-Foo", []byte(`T€st Cont€nt 123`), false},

I suspect the http client is sending the "ä" as literal UTF-8 bytes in the Host header, not as punycode or whatever.

[odeke-em]

@bradfitz which file/lines should this test be added to reproduce it? Or even the link, please?

[rsc]

We've lived a long time without this. We don't need to rush it into Go 1.6. Let's figure it out for Go 1.7. It's a huge topic.

[bradfitz]

Didn't happen for 1.7.

[rsc]

Brad, is this NeedsFix or NeedsDecision? Still for Go 1.8?

[bradfitz]

I did IDNA/Punycode already for Go 1.8. This was fixed by https://golang.org/cl/29072 (git rev b7e5303)