Description:
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---
From manual page: http://www.php.net/imagickdraw.polyline
---
polyline () and polygon () should accept arrays of the type:

[["x"=>0, "y"=>0], ["x"=>10, "y"=>10], ["x"=>20, "y"=>20], ...]

However if the array values are changed by array_walk () by reference, polyline () will not work in PHP 7, but does work in PHP <= 5.6.

Workaround is to call polyline on array_values ($array), instead of on $array itself, even if $array == array_values ($array) is true.

Test script:
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foreach (range (0, 100) as $ln) $pb[] = ['x'=>2*$ln, 'y'=>pow ($ln, 2)];
array_walk ($pb, function (&$v){$v['y'] = 200 - $v['y'] / 50;});
// following line returns true:
var_dump ($pb == array_values ($pb));
$im = new Imagick ();
$im->newImage (200, 200, "white");
$draw = new ImagickDraw ();
$draw->setFillColor ("none");
$draw->setStrokeColor ("black");
//Fatal error in PHP 7, but not in PHP <= 5.6
//$draw->polyline ($pb);
//Works in PHP 7, even if $pb == array_values ($pb) is true
$draw->polyline (array_values ($pb));
$im->drawImage ($draw);
$im->writeImage (getcwd (). "/test.png");
echo "<img src=\"test.png\">";

Expected result:
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Image with a parabola

Actual result:
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Fatal error