[Lazarus] Lazarus Make error under Ubuntu Mate

[Joe]

Hi,

under Ubuntu Mate 16.04.4 LTS with Lazarus 1.6 and FPC 3.0.0 I tried to 
make Lazarus, Revision 57978. Compiling was aborted with this error message:
'... guitestrunner.pas(682/24)  Error: (5083) Identifier idents no 
member "ChildTestCount"'.

How to fix?

--  Joe