The new doctesting framework (#12415) has revealed tab characters that weren't caught by the old. This ticket changes them to spaces.

Apply attachment: 13146_vs_51b5.patch and attachment: 13146_missed.patch

Component: doctest coverage

Author: David Roe

Reviewer: Keshav Kini, André Apitzsch, Jeroen Demeyer

Merged: sage-5.2.rc0

Issue created by migration from https://trac.sagemath.org/ticket/13146