BUG: clear temporary validation filename when validation ratio is set to 0

fix #1725 (closed)

Should be backported to release-6.6

mentioned in issue #1725 (closed)

mentioned in issue #1722 (closed)

Added to #1722 (closed) task list

Dashboard green, ready to merge

added 8 commits

• 95be5429...537b830f - 7 commits from branch develop
• f6c16ea5 - Merge branch 'develop' into fix_bug_1725

Compare with previous version

merged

mentioned in commit 314e8cb7

mentioned in commit 7043be58