This is a testcase for the fix for http://bugzilla.opendarwin.org/show_bug.cgi?id=7904. ReplaceSelectionCommand used to guess whether or not nodes in the fragment to be pasted were blocks. It now knows for sure. Before the fix, ReplaceSelectionCommand blew away content of the div below after copy/pasting it over itself.
This is a paragraph. This is another paragraph.