pop3d keeps mailbox locked

[Ken Olum]

I switched to using mailutils for pop and imap.  Imap seems OK, but
pop3d is keeping my mailbox locked even when it is not using it.

I'm using maildroid on my phone.  When I click refresh, it opens a
connection to pop3d (running under xinetd).  It successfully gets my
mail, but then the pop3d process sticks around, which is fine, but it
sticks around with the mailbox locked, i.e., there is a file
/var/mail/kdo.lock.  As a result, I can't get any new mail.

On a quick look with gdb it seems that the pop3d process is not in the
middle of doing anything.  It is in pop3d_readline in pop3d_mainloop.

I see nothing strange in my logs:

    TLS established using CHACHA20-POLY1305-AEAD (TLS1.2)
    POP3 login: user `kdo', source system
    Mar 24 11:42:47 olum pop3d[30343]: user `kdo' logged in with mailbox 
`/var/mail/kdo' (3 messages)

Of course I can work around this by getting everyone to use imap, which
seems not to have this problem and is probably better anyway, but it
seems like a serious bug.

                                        Ken