Previously pkg/singleflight
Imported from github.com/camlistore/go4/ at rev
039bcc4ca7e407e5611cbdf15a1f208be0bceda0
Also reimport vendor/go4.org/syncutil because some of it got split into
github.com/camlistore/go4/syncutil/syncdebug
Change-Id: Iaf48de71928d17e0410442ea6f5bef7262ba60d2
httputil.CloseBody closes a http.Response.Body nicely, such that it's
more likely to be re-used.
httputil.DecodeJSON parses JSON from a Response.Body and closes the
body. It also keeps a temporary copy of the input, for error messages.
Then use them everywhere, to improve HTTP TCP connection re-use.
And misc other clean-ups.
Change-Id: I5dc44be0165b13659459ed29ce5ab44c17d9739f
mpl