Make hg add foo; hg mv foo bar work. - foo will be removed (the user has a copy of its contents in bar) - bar will not be marked as a copy (there was no committed version of foo). We print a warning telling that to the user. Fixes issue269.

adding b
   rev    offset  length   base linkrev nodeid       p1           p2
     0         0       3      0       0 1e88685f5dde 000000000000 000000000000