Odd error message with MergeAllFaces

Running MergeAllFaces on an object produced this error message - although the command did complete. --Mitch

See this one:
http://discourse.mcneel.com/t/what-does-this-mean-and-should-i-care/26003

This message no longer shows here in the in-house ‘dailies’ so I’d guess the next WIP will not have it.

-Pascal