first parameter of CreateProcessA should be NULL in tinytest.c . If set you cannot run regress.exe using the name regress but if set to NULL Windopws will add .exe automatically. Using the first parameter to NULL is the recommended way to call CreateProcess:
http://msdn.microsoft.com/en-us/library/ms682425%28VS.85%29.aspx
But won't that just break it in any case where the path contains spaces?
Perhaps we'd be better off just adding the ".exe" to the commandname if it isn't there...