Description:
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I assign a complex object as a session variable, then the next time session_start() is called, it outputs a newline character (which should never happen).  

If I don't assign this object as a session variable, session_start() functions normally.  Any other action I've taken with $_SESSION produces the same results, unless I assign the complex object.

Reproduce code:
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// Page 1
$_SESSION["var"] = new MyComplexObject();

// Page 2
ob_start();
$len_before = ob_get_length();
session_start();
$len_after = ob_get_length();
ob_end_flush();

echo $len_before . "," . $len_after;

Expected result:
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Output: 0,0

Actual result:
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Output: [newline]
0,2