by raff367:

What steps will reproduce the problem?
If possible, include a link to a program on play.golang.org.

The test at http://play.golang.org/p/Yzayz9Fmuy returns different values in Go 1.2 vs.
Go 1.1.2

func main() {
        path := "a/b/c"
        u, _ := url.Parse(path)
        fmt.Println("path:", path)
        fmt.Println("url:", u.String())
 }

What is the expected output?

"a/b/c"

What do you see instead?

"/a/b/c"

Which version are you using?  (run 'go version')

go version devel +f4d1cb8d9a91 Thu Sep 19 22:34:33 2013 +1000 darwin/amd64

Please provide any additional information below.

The problem is caused by the "fix" for issue #11698045, that prepends a
"/" to the path in the String() method.
The correct fix is, I believe, to check if the buffer is empty or not. If it's empty the
original URL was a "relative URL" (no schema, no host, only path) in which
case the "/" should be omitted.

I have tested a fix, avaliable at https://golang.org/cl/14654045/
I have also updated the tests and added a new unit tests for similar cases ( build the
URL{} and check if String() returns the expected value)