Rename CVSNT "mergepoints" test and make it executable.
- rename test-convert-cvs-builtincvsps-cvsnt-mergepoints
(and related files) to test-convert-cvsnt-mergepoints
- this ensures that the test will be run, but does NOT make
it pass: in particularly, it fails regularly for me due
to the inconsistent behaviour of CVS itself
- expect "Branchpoints:" in debugcvsps output
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Ran 20 tests in 0.000s
OK