TestAttributedStringMerge: Add test case for 'hello' merge that failed in ProjectDemo today (it's reproducible too). The raw test case here passes though, not sure what causes the difference

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10022 7b3f36aa-e6db-49c1-8b4c-66eac1997e64