Comment 3 for bug 704219

FWIW, Hamcrest (Java) matchers append to a description, which might make this easier.

<http://www.google.com/codesearch#nmwoqoPm7yk/hamcrest-java/hamcrest-core/src/main/java/org/hamcrest/core/IsNot.java>

(Also, just discovered that there is a hamcrest Python port maintained by the hamcrest folk. Rather irritated by the news.)