Leon Stringer

PR #279 with proposed fix.

@jpahullo The commit for the PR to fix #275 is built upon the commit to fix this issue as 1) they're directly related, and 2) they both touch the same...

This looks like a duplicate of #275. There's a proposed fix in [leonstr/275-pgsqlsearch](https://github.com/leonstr/moodle-tool_mergeusers/tree/275-pgsqlsearch). @tibbakoi I think you can just replace `admin/tool/mergeusers/lib/mergeusersearch.php` with [the one from the above branch](https://github.com/leonstr/moodle-tool_mergeusers/blob/275-pgsqlsearch/lib/mergeusersearch.php).