Description:
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The title/code says it all. Once a variable is a string, using array access should 
mean char access, but this is not maintained for empty strings, while it's 
maintained for non-empty strings.

Test script:
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$a = ''; // empty string
$a[10] = 'a';
echo $a; // "Array"

$b = ' '; // non empty string
$b[10] = 'b';
echo $b; // "          b"

Expected result:
----------------
"          a"
"          b"

Actual result:
--------------
"Array"
"          b"