[root@salt-master pillar]# cat base/ssh.sls
#!yamlex
ssh: !aggregate
  keys: !aggregate
    - one: b
      two: a

[root@salt-master pillar]# cat group/ssh.sls
#!yamlex
!reset ssh: !aggregate
  !reset keys: !aggregate
    - three: a
      four: b

[root@salt-master pillar]# cat base/top.sls
base:
  '*':
    - ssh
group:
  '*':
    - ssh

[root@salt-master pillar]# salt 'qa-server*' pillar.items
qa-server:
    ----------
    ssh:
        ----------
        keys:
            |_
              ----------
              four:
                  b
              three:
                  a
            |_
              ----------
              one:
                  b
              two:
                  a


[root@salt-master pillar]# cat test.py
#!/usr/bin/python

from salt.utils.serializers.yamlex import serialize, deserialize

parseme = '''
ssh: !aggregate
  keys: !aggregate
    - one: b
      two: a

!reset ssh: !aggregate
  !reset keys: !aggregate
    - three: a
      four: b

'''

print deserialize(parseme)
[root@salt-master pillar]# python test.py
{ssh: {keys: [{three: a, four: b}]}}