I agree with you that JSON strings should be Unicode-encoded to begin with, so the call to utf8_encode() seems incorrect.

This was introduced by merging pull request https://github.com/mantisbt/mantisbt/pull/1 so I have asked the contributor to clarify why this was needed in the first place.

I believe this commit should be reverted.

I commented to https://github.com/mantisbt/mantisbt/pull/1 .

If you want to support bad implementations to send not Unicode-encoded strings, change url_get() in core/url_api.php

• detect encodings with "Content-Type" HTTP header.
• use iconv() or mb_convert_encoding() with detected encoding to encode to UTF-8 from other encodings.

note:
mb_detect_encoding() and passing "auto" to mb_convert_encoding() may return wrong result.

I tried to retrieve and parse logs from the contributor's repository.

$ curl 'https://api.github.com/repos/01-Scripts/01-Artikelsystem/commits?per_page=50' > commits.txt
$ file commits.txt
commits.txt: UTF-8 Unicode text
$ php -r 'var_dump(json_decode(file_get_contents("commits.txt")));' | grep 'ü'
(snip)
string(25) "Updatefile für 01article"
string(135) "0000692 Der Spaltenname 'text' und 'timestamp' ist ein reserviertes MySQL-Schlüsselwort
string(167) "#237 Verspäteter Bugfix. Ursprüngliche Änderung wurde nicht in die Installations .sql-Datei übernommen, sondern nur im Rahmen der Installationsroutine geändert..."
(snip)

...no problems without utf8_encode().

Michael (01-Scripts), the original contributor of this, change agreed to revert it [1]. Will do so shortly.

[1] https://github.com/mantisbt/mantisbt/pull/1#issuecomment-162825608