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
% reverting to rev 0
reverting foo
M foo
diff --git a/foo b/foo
old mode 100755
new mode 100644