error exporting contributions with soft credits
when trying to export contributions with soft credits I got the following error
unknown column 'Array' in 'group statement'
[civicrm 5.9; drupal 7.x; mariadb; php 7.1]
I traced it to line 152 of CRM/Export/BAO/Export.php
changing $groupBy = array('contribution_search_scredit_combined.id', 'contribution_search_scredit_combined.scredit_id'); to $groupBy = "contribution_search_scredit_combined.id, contribution_search_scredit_combined.scredit_id";
resolved the issue for me.
(I really need to learn how to do proper pull requests)