[bug-mailutils] IMAP read-only still expunges on close

[Dan Born]

mailbox_open with only the MU_STREAM_READ flag should open a mailbox
read-only, but when an IMAP mailbox is closed, it is also expunged.

The IMAP CLOSE command normally expunges, however the RFC also states:

"No messages are removed, and no error is given, if the mailbox is
 selected by an EXAMINE command or is otherwise selected read-only."

I don't know enough of the protocol to say how a mailbox is selected
read-only, but I think that should be the case when MU_STREAM_READ is
the only open flag. 

Is there anything I can do to disable the implicit expunge on close?

The server is courier-imap, if that matters.

Dan Born