Revision 1376

inserted sys.exit(1) into the tests so scons can detect the failure of the test. 
A similar statement has been removed from an earlier as it produces problems on 64bit Linux. Previously exit(0) was called in case of success but now this is not done in order to avoid a fatal end of the program. in the case of an error in the test there could be a fatal error so but I guess that this not really a problem.

PS: the fact that signal 0 was returned even for the case of an error lead to the illusion that all tests have been completed successfully.