Samba 4.1.6 not working after upgrade from 3.6.x - Fedora 20

[Gerhard Wiesinger]

Hello,

I upgraded from Fedora 17 (Samba 3.6.12) to Fedora 20 (Samba 4.1.6) and 
some shares are not working any more (I'm asked for password or not 
accessible message). I did not change anything in the config and the 
config is the same as in Fedora 17.

After some debugging I found the following error messages:
../source3/smbd/service.c:612(make_connection_snum)
   Connect path is '/shares/mm' for service [mm]
../libcli/security/dom_sid.c:208(dom_sid_parse_endp)
   string_to_sid: SID @users is not in a valid format

I also found a user with a similar problem (with no response):
[Samba] string_to_sid: SID <username> is not in a valid format
https://lists.samba.org/archive/samba/2013-June/174210.html

I tried to modify the config by removing the "valid users = @users" and 
it worked (see config mmtest share below).

So it looks to me like a bug in Samba 4.1.6. Can this bug be fixed?

Details can be found below.

Thank you.

Ciao,
Gerhard

Version in Fedora 20:
rpm -qa | grep -i samba | sort
samba-4.1.6-1.fc20.x86_64
samba-client-4.1.6-1.fc20.x86_64
samba-common-4.1.6-1.fc20.x86_64
samba-libs-4.1.6-1.fc20.x86_64
samba-winbind-4.1.6-1.fc20.x86_64
samba-winbind-clients-4.1.6-1.fc20.x86_64
samba-winbind-modules-4.1.6-1.fc20.x86_64
system-config-samba-1.2.100-2.fc20.noarch
system-config-samba-docs-1.0.9-6.fc20.noarch

# OK
[homes]
         comment = Home Directories
         valid users = %S
         write list = %S
         read only = No
         create mask = 0600
         directory mask = 0700
         browseable = No

# NOT OK
[mm]
         path = /shares/mm
# Causes problems here
         valid users = @users
         write list = gerhard
         force user = apache
         force group = apache
         create mask = 0644
         hide dot files = No

# OK
[mmtest]
         path = /shares/mm
         write list = gerhard
         force user = apache
         force group = apache
         create mask = 0644
         hide dot files = No