Use absolute paths in addremove.
This is more consistent with other places in the code, which only use
the "relpath" returned by cmdutil.walk for display purposes.
adding dir/bar
adding foo
dir/bar
foo
adding dir/bar_2
adding foo_2
dir/bar_2
foo_2
adding a
adding c
adding b
adding d
removing a
removing c
recording removal of a as rename to b (100% similar)