smbcacls keeps on looking for the configuration file in the default location: strace ./bin/smbcacls --configfile /tmp/pouet.conf 2>&1 | grep -E '(pouet|smb.conf)' execve("./bin/smbcacls", ["./bin/smbcacls", "--configfile", "/tmp/pouet.conf"], [/* 23 vars */]) = 0 stat("/usr/local/samba/etc/smb.conf", {st_mode=S_IFREG|0644, st_size=785, ...}) = 0 open("/usr/local/samba/etc/smb.conf", O_RDONLY) = The problems exists also in master.
Has been fixed with 49b500a61f0e1ed9d02654597c0785e7a1b933e9.