Sorry for the noise, seem that the root of evil is found after reading https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/553115. The gid for user messagebus from /etc/passwd was different from the gid of group messagebus in /etc/group. Edited manually and everything seems to work like a charm again, except the things I tried to fix be various workarounds in the meantime :(
Sorry for the noise, seem that the root of evil is found after reading https:/ /bugs.launchpad .net/ubuntu/ +source/ network- manager/ +bug/553115. The gid for user messagebus from /etc/passwd was different from the gid of group messagebus in /etc/group. Edited manually and everything seems to work like a charm again, except the things I tried to fix be various workarounds in the meantime :(