http client: reuse transport previously created in NewClient

[rht]

In case #1986 (comment) is a bug. Which is more likely, since the err "request cancelled" is supposed to be printed out https://github.com/ipfs/go-ipfs/blob/master/commands/http/client.go#L134.

[rht]

Which err, e.g. Error: Post http://127.0.0.1:5001/api/v0/get?arg=QmQv4YQNmRPuTTHs4AgBhKEFDdN7eQYeTbSmr8JVWVfury&encoding=json&stream-channels=true: net/http: request canceled needs to be humanized, related #560.

[whyrusleeping]

mmm. i think a lot of this was from before we used go1.5 http tralers to make things work right. We can probably get away with removing that cruft now

[rht]

Closing, since tr.CancelRequest is going to be replaced with the *http.Request.Cancel channel anyway, which has been around for ages (since go1.4).