The updated map for Mauritius Island available for Navigator FREE has got a bug. I believed first that it was due to a bug in the OSM map. But this is not the case as OsmAnd using the same OSM map source does not show the problem.
Between 2 roundabouts (20°17'12.2"S / 57°31'29.3"E and 20°19'15.6"S / 57°32'31.3"E), the existing motorway M1 cannot be used.
It seems that the conversion from the OSM source (which is correct) to the .mca maps failed somewhere.
I am using the latest version dated in November 201411130 and Navigator PC 14 to check the map.
When selecting the trip from Port-Louis to Mahebourg, the route leaves the motorway a few Km after Port Louis (around Curepipe) and goes back on the same motorway a few Km ahead between these 2 towns.