Problem: whatever is executed in a shell inside gnome terminal, is placed into `dbus.service' scope of systemd.

Test:

$ systemctl status
● pangea
    State: running
     Jobs: 0 queued
   Failed: 0 units
    Since: пт 2015-12-18 11:16:16 EET; 6h ago
   CGroup: /
           ├─init.scope
           │ └─1 /sbin/init
           ├─system.slice
           | └.....
           └─user.slice
             ├─user-1000.slice
             │ ├─user@1000.service
             │ │ ├─dbus.service
             │ │ │ ├─  ...
             │ │ │ ├─19103 zsh
             │ │ │ ├─19182 systemctl status
             │ │ │ └─19183 less
 ...

Symptoms: interactive tasks are now limited with `dbus.service' constraints. If anything too much resource intensive is launched (like build open embedded image), the task ends up in "can't fork: Resource temporarily unavailable").

Workaround:
1. Start tmux session from gnome shell: <alt-f2>tmux new-session -d
2. Start gnome terminal
3. Run tmux attach
Jobs will be run in `session-c2.scope' now.