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

%% Should show unknown
? unknown
removing b
%% Should show unknown and b removed
R b
? unknown
%% Should show a and unknown
a
unknown