Description of problem:
Even when input methods are defined through system dconf keyfile,
input methods do not work without gnome-inital-setup if the default shell is '/bin/sh'

Imagine an input-method class setting, 
gnome-initial-setup is disabled and input methods are predefined.

This setting does not work for all users. 
To sum up, it works when default shell is '/bin/bash',
but failed when the default shell is  '/bin/sh'


Version-Release number of selected component (if applicable):
ibus-1.5.3-13.el7
ibus-gtk2-1.5.3-13.el7
ibus-gtk3-1.5.3-13.el7
bash-4.2.46-28.el7

How reproducible:
always

Steps to Reproduce:
1. su as root
2. disable gnome-initial-setup
3. Define input method in system dconf db:

   a. Edit /etc/dconf/db/local.d/04-inputsource with following content:

     [org/gnome/desktop/input-sources]
     sources=[('xkb','jp'), ('ibus','kkc')]

   b. Update system dconf db
      dconf update

4. create a test user that use /bin/sh

   useradd -m --shell /bin/sh testuser
   
5. Re-login as testuser through gdm

6. Open gnome-terminal or any gtk application with an input area.
7. Switch to ibus-kkc and start typing


Actual results:
Still type in english.


Expected results:
Can type Japanese

Additional info:

## Workarounds

1. Set the default shell to /bin/bash
2. Specify gtk-im-module in dconf keyfile, like append following at /etc/dconf/db/local.d/04-inputsource


[org/gnome/desktop/interface]
gtk-im-module='ibus'