Description:
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According to documentation on "default-charset" (
http://php.net/manual/en/ini.core.php#ini.default-charset):

"The value of default_charset will also be used to set the default character set for ... mbstring functions if the mbstring.http_input mbstring.http_output mbstring.internal_encoding configuration option is unset."


This is true EXCEPT for mbstring.http_input! Querying all other settings will properly return "UTF-8" from the default-charset, but querying mbstring.http_input will return FALSE!

Test script:
---------------
<?php
declare(strict_types=1);

var_dump( ini_get( 'default_charset' ) ); // UTF-8 

var_dump( mb_internal_encoding() );      // UTF-8
var_dump( mb_http_output() );            // UTF-8
var_dump( mb_http_input() );             // FALSE
var_dump( mb_regex_encoding() );         // UTF-8

Expected result:
----------------
mb_http_input() should return the explicitly set default_charset (e.g., UTF-8).

Actual result:
--------------
mb_http_input() returns FALSE, even if default_charset is set to UTF-8.