Description:
------------
Insertions into a table with UNIQUE keys having a high occurrence of error 19 (constraint violation due to duplicate key) causes junk to be inserted. The test case reproduces the erroneous environment. The test keys are bound such that the column values MUST be "FIRSTx", "MIDx", and "LASTx". But the bad data shows inexplicable mix-ups in the order and sometimes junky contents. 

The test script is completely self-contained. Tested with stock Win10 PHP build:
PHP 7.0.32 (cli) (built: Sep 12 2018 15:54:04) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
SQLite 3.22.0 2018-01-22 18:45:57
zlib version 1.2.11

Test script:
---------------
<?php
define("SQLITE_CONSTRAINT", 19);   /* Abort due to constraint violation */

//	connect and configure session.

$data = new SQLite3("buggy");
$data->exec("pragma foreign_keys=on");
$data->exec("pragma recursive_triggers=on");
$data->exec("pragma journal_mode=off");
$data->exec("pragma synchronous=off");
$data->exec("pragma locking_mode=exclusive");
$data->exec("drop table if exists buggy");
$data->exec(<<<EOT
create table buggy (
	bug integer primary key autoincrement,
	bugfirst text,
	bugmid text,
	buglast text,
	unique (bugfirst, bugmid, buglast)
)
EOT
);
$data->exec("begin");

//	prepare sql.

$bugsql = $data->prepare("insert into buggy (bugfirst, bugmid, buglast) values (:bugfirst, :bugmid, :buglast)");
for ($i = $j = $k = 0; $i < 1000; $i += 1) {
		$bugfirst = "FIRST" . rand(1, 3);
		$bugmid = "MID" . rand(1, 5);
		$buglast = "LAST" . rand(1, 7);
		$bugsql->bindValue(":bugfirst", $bugfirst);
		$bugsql->bindValue(":bugmid", $bugmid);
		$bugsql->bindValue(":buglast", $buglast);
		@$insert = $bugsql->execute();
		$error = $data->lastErrorCode();
		echo "$bugfirst, $bugmid, $buglast, $error\n";
		if ($insert === false) {
			if ($error != SQLITE_CONSTRAINT) echo "Code $error.\n";
			$k += 1;
			continue;
		}
		$bug = $data->lastInsertRowID();
		$j += 1;
}
$data->exec("commit");
$data->close();
echo "looped $i, inserted $j, clashed $k.\n";
exit;
?>

Expected result:
----------------
All inserted column values must be like this:
"FIRSTx", "MIDx", and "LASTx". And all triplet values are to be unique.

Actual result:
--------------
But when unique key violations occur, rows are inserted with key values out-of-order, or just junk. Example:

PK	key1	key2	key3
129	FIRST3	MID2	LAST4
130	MID5	LAST	LAST3
131	MID2	LAST	LAST5
132	MID1	LAST	LAST3
133	LAST4	LAST	MID1
134	FIRST3	MID2	LAST2
135	FIRST2	MID5	LAST3
136	MID2	LAST	LAST1
137	LAST4	MID5	:bugm
138	MID1	LAST	LAST7
139	MID1	LAST	LAST1
140	FIRST2	MID5	LAST2
141	LAST7	LAST	MID1
142	LAST1	LAST	MID4