test-mv-cp-st-diff: avoid linkrev collisions
The copy detection code relies heavily on the linkrevs, so it's better
to avoid collisions in this test.
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding b
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding b