convert: clear the dirstate before a conversion, invalidate it afterwards
Clearing it before the conversion protects us from whatever data were
there (file copies in particular).
Invalidating it after the conversion avoids writing a possibly
inconsistent dirstate to disk.
adding da/foo
adding foo
% manifest
200 Script output follows
drwxr-xr-x da
-rw-r--r-- 4 foo
200 Script output follows
-rw-r--r-- 4 foo