Revert "detect_well_known_errors - Fix problem re parsing for python 2.6."

This reverts commit 0c669f87fa8f4bce6596bad043b8ab297ab484a8.
Revert "Revert Python 2.7 requirement upgrade, and remove dwke options."

This reverts commit c148081f78b8e12f258a77fe68b1125cd51fd3b6.
remove remaining support for $libdir/python2.6/dist-packages

Signed-off-by: Andreas Beckmann <anbe@debian.org>