At the end of testing when reporting the results, sage -t does not take into account the current directory. It produces output like this:
sage -t devel/sage-combinat/sage/combinat/root_system/ambient_space.py
sage -t devel/sage-combinat/sage/combinat/root_system/root_lattice_realization.py
sage -t devel/sage-combinat/sage/combinat/root_system/root_space.py
sage -t devel/sage-combinat/sage/combinat/root_system/root_system.py
sage -t devel/sage-combinat/sage/combinat/root_system/weight_space.py
when it should be giving output like
sage -t ambient_space.py
sage -t root_lattice_realization.py
sage -t root_space.py
sage -t root_system.py
sage -t weight_space.py
if I am in $SAGE_ROOT/devel/sage-combinat/sage/combinat/root_system .