Oops. It's not actually been testing anything. You can tell because it
tried to run the wrong program.
Fortunately, once this is fixed, the test does seem to run OK.
mdup=BUILDDIR/t/mdup.t
## Very simple cases.
-$mdup 3:4
-$mdup 4:3
+AT_CHECK([$mdup 3:4])
+AT_CHECK([$mdup 4:3])
## Overlapping sources and destinations
-$mdup 4:3 3:5 5:6
+AT_CHECK([$mdup 4:3 3:5 5:6])
## Repeated sources
-$mdup 3:4 3:3 3:-1
-$mdup 5:8 3:4 3:5 4:6
+AT_CHECK([$mdup 3:4 3:3 3:-1])
+AT_CHECK([$mdup 5:8 3:4 3:5 4:6])
## Cycles
-$mdup 5:7 3:4 3:5 4:6 5:3
-$mdup 5:8 3:4 3:5 4:6 5:3
+AT_CHECK([$mdup 5:7 3:4 3:5 4:6 5:3])
+AT_CHECK([$mdup 5:8 3:4 3:5 4:6 5:3])
AT_CLEANUP