fix some rename/copy bugs - delete copy information when we update dirstate hg was keeping the copy state and marking things as copied on multiple commits - files that are renamed should have no parents if you do a rename/copy to an existing file, it should not be marked as descending from its previous revisions. - remove spurious print from filelog.renamed - add some more copy tests

merging for b
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This is file b1
merging for b
merging b
merging for b
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