[conformal/btcwire] d0dfff: fix typo in test: use %s for strings

[David Hill]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcwire
  Commit: d0dfff8292cd09e85db4ff5da0732115ff93f1a8
      
https://github.com/conformal/btcwire/commit/d0dfff8292cd09e85db4ff5da0732115ff93f1a8
  Author: David Hill <dh...@conformal.com>
  Date:   2014-02-04 (Tue, 04 Feb 2014)

  Changed paths:
    M common_test.go

  Log Message:
  -----------
  fix typo in test: use %s for strings