test-copies: test that copies' sidedata does not get corrupted during pull
This is an important usecase.
Differential Revision: https://phab.mercurial-scm.org/D10347
test-copies: simplify some conditional output
Now that all computation using sidedata give the same result, we can
simplify conditional
Differential Revision: https://phab.mercurial-scm.org/D10346