ethereum/go-ethereum — pull request #202 by fjl (2014-12-09 10:20:16+00:00)
Title: RLP: remove support for signed ints and other fixes

There is no canonical encoding for signed integers. They don't mix well with the 'no leading zeros` rule.
Given that RLP is part of consensus I think it's better to leave them unsupported and
define an encoding later, when some protocol requires negative numbers (could be never).

An alternative solution would be to return an error for negative values.