tests/test-copy2.out

fix traceback of extdiff after a merge

- files that comes from a different branch are marked as modified
  but aren't present in the original manifest
- add a testcase for extdiff and for regular diff

# should show copy
copy: foo -> bar
# shouldn't show copy
# should match
   rev    offset  length   base linkrev nodeid       p1           p2
     0         0       5      0       0 2ed2a3912a0b 000000000000 000000000000
renamed from foo:2ed2a3912a0b24502043eae84ee4b279c18b90dd
# should not be renamed
not renamed
# should show copy
copy: foo -> bar
# should show no parents for tip
   rev    offset  length   base linkrev nodeid       p1           p2
     0         0      69      0       1 6ca237634e1f 000000000000 000000000000
     1        69       6      1       2 7a1ff8e75f5b 6ca237634e1f 000000000000
     2        75      82      1       3 243dfe60f3d9 000000000000 000000000000
# should match
   rev    offset  length   base linkrev nodeid       p1           p2
     0         0       5      0       0 2ed2a3912a0b 000000000000 000000000000
     1         5       7      1       2 dd12c926cf16 2ed2a3912a0b 000000000000
renamed from foo:dd12c926cf165e3eb4cf87b084955cb617221c17
# should show no copies