Description:
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preg_replace changes replaced string encoding when replacement parameter is double quoted.

Reproduce code:
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$source = 'asdfasd asdf asdf [company=456[replacement]] asdf';
echo preg_replace('~\[\s*company=([0-9]+)\[\s*([^\]]+\s*)\]\]~', '\2', $source);
echo preg_replace('~\[\s*company=([0-9]+)\[\s*([^\]]+\s*)\]\]~', "\2", $source);

Expected result:
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asdfasd asdf asdf replacement asdf
asdfasd asdf asdf replacement asdf

Actual result:
--------------
asdfasd asdf asdf replacement asdf
asdfasd asdf asdf  asdf