Fix bug 740: overflow issue in stableNorm
(grafted from 7741139053397d6fdadd64ca7daf12d0b376dc62)

--HG--
branch : 3.2
extra : source : 7741139053397d6fdadd64ca7daf12d0b376dc62
Fix stable_norm unit test for complexes
(grafted from 5a3d485fdef1d1badf65b30a522e55b3f34f5135)

--HG--
branch : 3.2
extra : source : 5a3d485fdef1d1badf65b30a522e55b3f34f5135