GO_GAE建立Go-Playground错误

I wanna upload go-playground to my own GAE to code with go online. Firstly, I use the command goapp serve and it returns Can't find package "code.google.com/p/go.tools/godoc. Then, I download it, go get code.google.com/p/go.tools/cmd/godoc; But then, when I retry goapp serve command and it shows this: gocode/src/code.google.com/p/go.tools/astutil/enclosing.go:435: n.Lparen undefined (type *ast.TypeAssertExpr has no field or method Lparen); I try to fix this with go1.1 & go1.2 and it doesn't work. I'm a fresh man with go, can anyone help me with this? thx.

Godoc requires Go 1.2, but Go App Engine only picks up Go 1.2 from App Engine 1.9.0. You'll either need to wait for that, or upload with api_version: go1.2beta.