TypeError: sequence item 1: expected string, NoneType found

[Martin Pool]

This is https://bugs.launchpad.net/bzr/+bug/120968 "bzr update" in
checkout of empty branch fails and breaks dirstate

Steve's repoduction shows this is actually doing the wrong merge into
the working directory which causes these files to be deleted.

Wouter, you have this marked 'in progress', do you have any code we
can look at or some ideas on how to fix it?

-- 
Martin