Description of problem:
Using the implementation of the libc-client library in php-imap, the mail_search_full function always returns false.

Version-Release number of selected component (if applicable):
latest

How reproducible:
<?php
ini_set('display_errors', 'On');
error_reporting(E_ALL);
include 'settings.php';
echo '<pre>';
echo shell_exec('cat /etc/redhat-release') . "\n";
echo 'PHP ' . phpversion() . "\n";
$inbox = 'INBOX';
$_mailbox = '{%s/imap/notls/norsh/novalidate-cert/readonly}%s';
$mailbox = sprintf($_mailbox, $host, $inbox);
$stream = imap_open($mailbox, $user, $pass, OP_SILENT);
echo "imap_mailboxmsginfo->Nmsgs\n";
var_dump(imap_mailboxmsginfo($stream)->Nmsgs);
echo "\n";
$search = 'ALL';
echo "imap_search $search\n";
var_dump(imap_search($stream, $search)); //bool(false)
if (imap_last_error()) {
    echo 'Error: ' . imap_last_error() . "\n";
}
echo "\n";
echo "imap_alerts\n";
var_dump(imap_alerts());
echo "imap_errors\n";
var_dump(imap_errors());
?>

Actual results:
CentOS release 6.6 (Final)

PHP 5.4.33
imap_mailboxmsginfo->Nmsgs
int(100)

imap_search ALL
bool(false)
Error: SECURITY PROBLEM: insecure server advertised AUTH=PLAIN

imap_alerts
bool(false)
imap_errors
array(1) {
  [0]=>
  string(55) "SECURITY PROBLEM: insecure server advertised AUTH=PLAIN"
}

Expected results:
imap_search should return an array of message numbers or UIDs.

If it failed, I would expect there to be a fatal error.