t.write("a.cpp", "int main() { return 0; }\n")
t.write("build/Jamfile", "exe a : ../a.cpp ; ")
t.run_build_system(subdir="build")
t.write("a.cpp", "int main() { return 0; }\n")
t.write("build/Jamfile", "exe a : ../a.cpp ; ")
t.run_build_system(subdir="build")