- do_addremove: use local variable instead of an attribute (cosmetic)
- do_addremove: fixed "corner case"

Assume $PWD/x is a directory and /path/to/pkg/x is an unversioned file.
Without this fix, "osc ar /path/to/pkg" did not add the file "x".
- do_addremove: if a "deleted" file exists in the wc, track it again