[BUG] pygit2 package install fails on Debian

[dafyddj]

Your setup

Formula commit hash / release tag

a333801

Versions reports (master & minion)

Salt Version:
               Salt: 2019.2.5

    Dependency Versions:
               cffi: Not Installed
           cherrypy: Not Installed
           dateutil: 2.5.3
          docker-py: Not Installed
              gitdb: 2.0.0
          gitpython: 2.1.1
              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: 3.5.3 (default, Sep 27 2018, 17:25:39)
       python-gnupg: Not Installed
             PyYAML: 3.12
              PyZMQ: 16.0.2
               RAET: Not Installed
              smmap: 2.0.1
            timelib: Not Installed
            Tornado: 4.4.3
                ZMQ: 4.2.1

    System Versions:
               dist: debian 9.12 
             locale: UTF-8
            machine: x86_64
            release: 4.19.76-linuxkit
             system: Linux
            version: debian 9.12 

Pillar / config used

  lookup:
    libgit2: libgit2-24
    gitfs:
      pygit2:
        install_from_source: false
    python_git: python3-git

---

Bug details

Describe the bug

salt.pygit2 has no default value.

Steps to reproduce the bug

root@d82b04a995a0:~# salt-call -c /tmp/kitchen/etc/salt/ state.show_sls salt.gitfs.pygit2 --out=yaml
# [ERROR   ] Rendering exception occurred
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/salt/utils/templates.py", line 394, in render_jinja_tmpl
    output = template.render(**decoded_context)
  File "/usr/lib/python3/dist-packages/jinja2/environment.py", line 1008, in render
    return self.environment.handle_exception(exc_info, True)
  File "/usr/lib/python3/dist-packages/jinja2/environment.py", line 780, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/lib/python3/dist-packages/jinja2/_compat.py", line 37, in reraise
    raise value.with_traceback(tb)
  File "<template>", line 79, in top-level template code
jinja2.exceptions.UndefinedError: 'dict object' has no attribute 'pygit2'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/salt/utils/templates.py", line 169, in render_tmpl
    output = render_str(tmplstr, context, tmplpath)
  File "/usr/lib/python3/dist-packages/salt/utils/templates.py", line 404, in render_jinja_tmpl
    buf=tmplstr)                                                                                         
salt.exceptions.SaltRenderError: Jinja variable 'dict object' has no attribute 'pygit2'
# [CRITICAL] Rendering SLS 'base:salt.gitfs.pygit2' failed: Jinja variable 'dict object' has no attribute 'pygit2'
local:                     
- 'Rendering SLS ''base:salt.gitfs.pygit2'' failed: Jinja variable ''dict object''
  has no attribute ''pygit2'''

Expected behaviour

No traceback.

Attempts to fix the bug

Additional context