Bug report

Bug description:

The Babyl message file format supported by the mailbox module has two sections for headers; a "full" header section and a "visible" headers section. Software that uses the Babyl software natively interprets an empty "full" header section as meaning that the visible and full headers are identical, so they don't have to be stored twice in the file. The Python module doesn't do this; if it encounters a message in a Babyl file which has nothing between the labels line and the '*** EOOH *** line, it creates a message object with no headers. Instead, in this case it should interpret the headers after the *** EOOH *** line as full headers for the message.

CPython versions tested on:

3.12

Operating systems tested on:

Linux