AT_CHECK([$mdup 3:4])
AT_CHECK([$mdup 4:3])
-## Overlapping sources and destinations
+## Overlapping sources and destinations.
AT_CHECK([$mdup 4:3 3:5 5:6])
-## Repeated sources
+## Repeated sources.
AT_CHECK([$mdup 3:4 3:3 3:-1])
AT_CHECK([$mdup 5:8 3:4 3:5 4:6])
-## Cycles
+## Cycles.
AT_CHECK([$mdup 5:7 3:4 3:5 4:6 5:3])
AT_CHECK([$mdup 5:8 3:4 3:5 4:6 5:3])