rust-lang/rust — pull request #19887 by alexcrichton (2014-12-15 17:10:04+00:00)
Title: serialize: Change some FnOnce bounds to FnMut

Relax some of the bounds on the decoder methods back to FnMut to help accomodate
some more flavorful variants of decoders which may need to run the closure more
than once when it, for example, attempts to find the first successful enum to
decode.