Add fshttp.SetFaultInjector, which installs a function consulted by
every Transport before a request is sent. The injector can synthesise
an error status code or a transport error for chosen requests. The
request body is drained and closed as a real round trip would, but
nothing reaches the server.
This lets the integration tests check that backends cope with a
transient failure part way through an upload - in particular that a
retry re-sends the same data rather than an already consumed or
freed buffer - without needing a fake server for each backend.
Nick Craig-Wood
8d8b82ba6f