Description:
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When full arcs are to be drawn (i.e. $start = 0 and $end = 360),
imagearc() calls gdImageEllipse() internally. However,
gdImageEllipse() does not yet support thickness, so the behavior
is inconsistent with partial arcs.


Test script:
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<?php
$im = imagecreatetruecolor(100, 100);
imagesetthickness($im, 5);
imagearc($im, 50, 50, 90, 90, 0, 360, 0xffffff);
imagepng($im, '72603.png');


Expected result:
----------------
A thick arc.

Actual result:
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A thin arc.