When creating the archive "somename.extension" out of an existing directory called "somename", it is no longer enough to just tyoe "somename" in the filechooser entry and have Xarchiver append the appropriate extension. The filechooser now assumes that you really wanted to cd into "somename". I have tried convincing the GTK+ devs to revert this https://bugzilla.gnome.org/show_bug.cgi?id=638528 but they seem unwilling.
Attached is a patch which prevents the user from having to type the extension to get around this. This is related to my other patch that also allows the user to get away with typing much less: http://sourceforge.net/tracker/?func=detail&aid=2847595&group_id=140153&atid=745600