Bug 19335: Fix 00-merge-conflict-markers.t when dockerised

Bug 19335: Fix 00-merge-conflict-markers.t when dockerised

This does not make sense, but fix a bug (why?)
Without this patch, the tests failed on po files:

[17:14:26] t/00-merge-conflict-markers.t .. Failed 1/1 subtests
Test Summary Report
-------------------
t/00-merge-conflict-markers.t (Wstat: 9 Tests: 0 Failed: 0)
  Non-zero wait status: 9
  Parse errors: Bad plan.  You planned 1 tests but ran 0.
Result: FAIL

Note that this is not related to bug 19227.

if the ^>>>>>> and ^<<<<<< matches are done on the same line, the test fail
As saw it failed on *-pref.po files
  misc/translator/po/kn-Knda-pref.po
  misc/translator/po/ja-Jpan-JP-pref.po
  misc/translator/po/nl-BE-pref.po
  misc/translator/po/sr-Cyrl-pref.po

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 0d03f143e25f498de780d2ddd1972c3be7947519)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>