Here are the steps to reproduce:

cpages@pica:~/repos/test$ find .
.
./a
./a/f
./_FOSSIL_
cpages@pica:~/repos/test$ fossil changes
cpages@pica:~/repos/test$ mkdir b
cpages@pica:~/repos/test$ fossil mv a/f b
RENAME a/f b/f
cpages@pica:~/repos/test$ mv a/f b
cpages@pica:~/repos/test$ fossil changes
RENAMED    b/f
cpages@pica:~/repos/test$ find .
.
./a
./_FOSSIL_
./b
./b/f
### do some changes in the repository ###
cpages@pica:~/repos/test$ fossil update
ADD a/f
REMOVE b/f
ADD ff
--------------
updated-to:   9c598efdab6b4523d91d36cd6142e688a42c1e44 2010-12-28 07:49:47 UTC
tags:         trunk
comment:      Adding file. (user: cpages)
cpages@pica:~/repos/test$ find .
.
./a
./a/f
./_FOSSIL_
./b
./ff
cpages@pica:~/repos/test$ fossil changes
cpages@pica:~/repos/test$