Remove separate check/drop from Export, moving it into the patch dumping code.  This allows us to recreate all the intermediate pristines/inventories so we can later reset back to them. This is needed in the case of an incremental export of a new branch that is based on an already-exported state.
Remove separate check/drop from Export, moving it into the patch dumping code. 
This allows us to recreate all the intermediate pristines/inventories so we can
later reset back to them. This is needed in the case of an incremental export
of a new branch that is based on an already-exported state.


nh2/darcs-fastconvert