Fix :Hgvdiff with a file that is a copy. Previously, :Hg rename old new :" (A rename is a copy and a deletion of the file with the old name.) :edit new :Hgvdiff " "new: no such file in rev NNNN" was displayed in the window to the right of the new vertical split. Now :Hgvdiff diffs new with old from the head revision.

f535cda5d20e7a8e8ec5d9946bea4dbc630be7e1 0.3.0
cac06d16dafcbdd139dd491132d85cd0c7ea8a0a 0.3.1
e4e29a1da13c0d95d6ed43aa88209295e3d99d97 0.4.0