Description:
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ENG: Functions for working with strings return different types. Because of this, for example, function strtr not working properly.

RUS: ??????? ??? ?????? ?? ???????? ?????????? ?????? ???? ????????. ??-?? ????? ?????? ???????, ???????? strtr, ???????? ???????????.

Reproduce code:
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$sour = 'hello';

ob_start();
echo $sour;
$buff = ob_get_clean();

var_dump($sour);
var_dump($buff);

var_dump($sour === $buff);
var_dump(substr($buff,0));

var_dump(strtr($buff, array($sour => 'HELLO')));
var_dump(strtr($buff, $sour, 'HELLO'));

Expected result:
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unicode(5) "hello"
string(5) "hello"
bool(false)
string(5) "hello"
string(5) "hello"
unicode(5) "HELLO"

Actual result:
--------------
unicode(5) "hello"
unicode(5) "hello"
bool(true)
unicode(5) "hello"
unicode(5) "HELLO"
unicode(5) "HELLO"