Current way was expecting return values that are not present in slaves

Comments, trailing spaces, dead code

- No need of so much debug
- remove dead code
- Indent

Useless because it happens only with locally hacked slapos.core.

Squashed commits are evil
Squashed commits are evil
Squashed commits are evil
Squashed commits are evil

This is a consequence of f4d0a1f68829 commit.

This is a squash merge of 'resiliency-testing' branch when
the HEAD of this branch was f725c81d7d69.

The merge was done by Antoine Catton.

This reverts commit fdb2b87b.
This breaks erp5 test runner (maybe it does not accept IPv6 in SQL
connection strings).

Also, make it optional.

Unused since egg bump from commit 80bfb5e0 .