Encoding to Greek OEM 737 character set is broken

Up until version 7.5.1, the display conversion to OEM 737 (Greek DOS codepage) worked fine. From version 7.5.2 this conversion function is broken.

Steps to Reproduce the Issue

1. Open a file that contains Greek written from a DOS window (copy con ....) in Notepad++ 7.5.2+.
2. Click on Encoding -> Character Sets -> Greek -> OEM 737.
3. You should see the Greek characters displayed, but instead you see another character set.

Debug Information

Notepad++ v7.5.3 (64-bit)
Build time : Dec 5 2017 - 10:47:54
Path : C:\Program Files\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : OFF
OS : Windows 7 (64-bit)
Plugins : DSpellCheck.dll mimeTools.dll NppConverter.dll