Sieve: Invalid/unknown path to storage

[Kay-Michael Voit]

Hi, I have just updated from Ubuntu 15.04 to 15.10. Unfortunately, sieve 
scripts are not recognized anymore.

Here is my version:
> dovecot --version
> 2.2.18
> apt-cache policy dovecot-sieve
> dovecot-sieve:
>   Installed: 1:2.2.18-2ubuntu2
>   Candidate: 1:2.2.18-2ubuntu2
>   Version table:
>  *** 1:2.2.18-2ubuntu2 0
>         500 http://us.archive.ubuntu.com/ubuntu/ wily/main amd64 Packages
>         100 /var/lib/dpkg/status

And this is the log entry:
> Dec 25 09:24:12 home-le dovecot: lda(user1): Warning: sieve: file 
> storage: Active sieve script symlink /home/user1/.dovecot.sieve is 
> broken: Invalid/unknown path to storage (points to /home/user1/sieve).
> Dec 25 09:24:12 home-le dovecot: lda(user1): 
> msgid=<567CFD2C.7070301 at example.org>: saved mail to INBOX
> Dec 25 09:24:12 home-le postfix/local[28536]: 70876BD035A: 
> to=<user1 at example.org>, relay=local, delay=0.07, 
> delays=0.02/0.01/0/0.04, dsn=2.0.0, status=sent (delivered to command: 
> /usr/lib/dovecot/deliver -c /etc/dovecot/dovecot.conf -m "${EXTENSION}")

It is not a permission issue (though there should even be one with more 
restrictive permissions)
> otheruser at home-le:~$ cat /home/user1/.dovecot.sieve
> require ["variables","date", "include"];
>
> include :personal "00-delete";
> include :personal "01-spam";
> include :personal "50-bulk_filter";

It is apparently also not a path normalization issue (also according to 
the correct "points to" path in the log). I used an absolute path in the 
symlink:
> user1 at home-le:~$ ls -la .dovecot.sieve
> lrwxrwxrwx 1 user1 user1 33 Dec 25 09:23 .dovecot.sieve -> 
> /home/kay/sieve/managesieve.sieve

Any idea what could be wrong here?

Here is my dovecot -n output:
> namespace inbox {
>   inbox = yes
>   location =
>   mailbox Drafts {
>     special_use = \Drafts
>   }
>   mailbox Junk {
>     special_use = \Junk
>   }
>   mailbox Sent {
>     special_use = \Sent
>   }
>   mailbox "Sent Messages" {
>     special_use = \Sent
>   }
>   mailbox Trash {
>     special_use = \Trash
>   }
>   prefix =
>   separator = .
>   type = private
> }
> passdb {
>   driver = pam
> }
> plugin {
>   sieve = file:~/.dovecot.sieve
>   sieve_dir = ~/sieve
> }
> postmaster_address = postmaster at example.net
> protocols = " imap sieve"
> service managesieve-login {
>   inet_listener sieve {
>     port = 4190
>   }
> }
> ssl_ca = </etc/ssl/certs/startssl.ca.pem
> ssl_cert = </etc/ssl/certs/net.example.home-le.pem
> ssl_key = </etc/ssl/private/net.example.home-le.key
> submission_host = 192.168.153.1
> userdb {
>   driver = passwd
> }
> protocol lda {
>   mail_plugins = " sieve"
> }
> protocol imap {
>   mail_max_userip_connections = 50
> }