[conformal/btcd] 931408: Improve non-standard tx error message.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcd
  Commit: 93140802ba2cc4e70e128549b60734c710334f40
      
https://github.com/conformal/btcd/commit/93140802ba2cc4e70e128549b60734c710334f40
  Author: Dave Collins <da...@conformal.com>
  Date:   2014-03-17 (Mon, 17 Mar 2014)

  Changed paths:
    M mempool.go

  Log Message:
  -----------
  Improve non-standard tx error message.

This commit removes the word "only" from the non-standard transaction
error message when the number of items on the stack does not match the
number of expected items.

This was suggested by @mbelshe.