pillar changed after upgrade from 2018.3.4 to 2019.2.0

[tigpas]

Description of Issue/Question

My pillar are merged on another way after upgrade from 2018.3.4 to 2019.2.0.

Setup

top.sls

base:
  '*':
    - default

default/init.sls

include:
  - default.test
  - default.test2

default/test.sls

test:
  a: 2
  c: 2

default/test2.sls

test:
  a: 3
  b: 3

Results

2018.3.4: This is my expected result. First, test.sls are included; second, test2.sls overwrite "test.a" with "3".

local:
    ----------
    test:
        ----------
        a:
            3
        c:
            2
        b:
            3

2019.2.0: The value of "test.a" is now "2".

local:
    ----------
    test:
        ----------
        a:
            2
        b:
            3
        c:
            2

Changing the order of the includes in "default/init.sls" changed the result for 2018.3.4, but I get the same result in 2019.2.0

Versions Report

Salt Version:
           Salt: 2018.3.4
 
Dependency Versions:
           cffi: Not Installed
       cherrypy: Not Installed
       dateutil: 2.5.3
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.9.4
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: Not Installed
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.4.8
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.13 (default, Sep 26 2018, 18:42:22)
   python-gnupg: Not Installed
         PyYAML: 3.12
          PyZMQ: 16.0.2
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.4.3
            ZMQ: 4.2.1
 
System Versions:
           dist: debian 9.6 
         locale: UTF-8
        machine: x86_64
        release: 4.9.0-8-amd64
         system: Linux
        version: debian 9.6 

Salt Version:
           Salt: 2019.2.0
 
Dependency Versions:
           cffi: Not Installed
       cherrypy: Not Installed
       dateutil: 2.5.3
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.9.4
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: Not Installed
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.4.8
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.13 (default, Sep 26 2018, 18:42:22)
   python-gnupg: Not Installed
         PyYAML: 3.12
          PyZMQ: 16.0.2
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.4.3
            ZMQ: 4.2.1
 
System Versions:
           dist: debian 9.6 
         locale: UTF-8
        machine: x86_64
        release: 4.9.0-8-amd64
         system: Linux
        version: debian 9.6 

[max-arnold]

Probably the same problem as #52134

[dmurphy18]

Closing this since similar to #52134, additional changes in this area of already been made since 2019.2.0 release which should help to address this issue.