tests: fix rename subdir check that was failing in travis

The issue begun after commit 0f85e0535bd4e6d19fadca182e4d57660b6bb57b and
it seems removal of == markings I used as check output header highlights
were somehow travis to break.

Reference: https://travis-ci.org/karelzak/util-linux/builds/30538376
Signed-off-by: Sami Kerola <kerolasa@iki.fi>