Normalize `url.Error` message for Go 1.14
Normalize `url.Error` message for Go 1.14

Go 1.13: `Post <URL>: <message>`
Go 1.14: `Post "<URL>": <message>`

Since we have an existing test that includes this error message, make
sure that `url.Error`s are output without quotes around the URL.

github/hub,github/hub,github/hub,github/hub