If i_buffer_read() fails because of EOF, set buf_errno to 0.
If i_buffer_read() fails because of EOF, set buf_errno to 0.

LTD-Beget/dovecot,damoxc/dovecot,Distrotech/dovecot,damoxc/dovecot,Distrotech/dovecot,damoxc/dovecot,Distrotech/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,damoxc/dovecot,LTD-Beget/dovecot,Distrotech/dovecot,damoxc/dovecot,Distrotech/dovecot,LTD-Beget/dovecot