Also, 'make ptestlong' gave this:
sage -t --long --warn-long 62.7 --random-seed=0
src/sage/doctest/test.py # 7 doctests failed
sage -t --long --warn-long 62.7 --random-seed=0
src/sage/tests/cmdline.py # 2 doctests failed
and then
=============================================================== ERRORS
================================================================
_________________________________________ ERROR collecting
sage/structure/sage_object_test.py
_________________________________________
ImportError while importing test module
'/home/john/sage/src/sage/structure/sage_object_test.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
src/sage/structure/sage_object_test.py:3: in <module>
from .sage_object import SageObject
E ImportError: attempted relative import with no known parent package
======================================================= short test
summary info =======================================================
ERROR src/sage/structure/sage_object_test.py
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error
during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
========================================================== 1 error in
3.81s ===========================================================
make: *** [Makefile:201: ptestlong] Error 1
which seems to show something not working in the test infrastructure.