[dovecot/core] 25e461: lib-storage: Fail if no namespaces have list=yes

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: 25e4617fb7374331411baece15af67aeecacf922
      https://github.com/dovecot/core/commit/25e4617fb7374331411baece15af67aeecacf922
  Author: Timo Sirainen <timo.sirainen at dovecot.fi>
  Date:   2016-11-25 (Fri, 25 Nov 2016)

  Changed paths:
    M src/lib-storage/mail-namespace.c

  Log Message:
  -----------
  lib-storage: Fail if no namespaces have list=yes

The previous check allowed all namespaces to have list=children. This
crashed later on in mail_namespaces_get_root_sep(), because it couldn't
find any list=yes namespaces.