py-numpy: update (#8003)

* py-numpy: update

* Better constrain when can / cannot parallel build.

* Update SciPy parallel logic to be specific to Python 3.5+, same as in Numpy.

var/spack/repos/builtin/packages/py-scipy/package.py

@@ -74,9 +74,10 @@ def build_args(self, spec, prefix):
         args = []
 
         # Build in parallel
-        # Known problems with Python 3
+        # Known problems with Python 3.5+
+        # https://github.com/spack/spack/issues/7927
         # https://github.com/scipy/scipy/issues/7112
-        if not spec.satisfies('^python@3:'):
+        if not spec.satisfies('^python@3.5:'):
             args.extend(['-j', str(make_jobs)])
 
         return args