Bug 1629: Failure when binary file is attempted to be opened in an internal editor on system with multibyte legacy encoding

https://winscp.net/tracker/1629
(cherry picked from commit acba183ed9059c91233b20741e7e5042f206d220)

Source commit: 7cdfa7d7d023ea0a4a1d4d3ece593f2ffefe02cc

source/forms/Editor.cpp

@@ -1301,7 +1301,7 @@ void __fastcall TEditorForm::LoadFromFile(bool PrimaryEncoding)
       {
         UnicodeString Message = FMTLOAD(EDITOR_ENCODING_ERROR, (FFileName, FEncodingName));
 
-        if (CanTrySecondary)
+        if (PrimaryEncoding && CanTrySecondary)
         {
           TEncoding * EncodingBackup = FEncoding;
           UnicodeString EncodingNameBackup = FEncodingName;