feat(kitchen): avoid using bootstrap for master instances

* https://travis-ci.org/myii/template-formula/builds/645908860
* saltstack/salt-bootstrap#1424 (comment)

ssf/defaults.yaml

@@ -21,10 +21,10 @@ ssf_node_anchors:
             #       the release phase via. `pre-commit_semantic-release.sh`
             #       An alternative method could be to use:
             #       `git describe --abbrev=0 --tags`
-            # yamllint disable rule:line-length
-            title: 'refactor: improve reusability using an unique keyword TEMPLATE'
-            body: '* Checked using https://github.com/myii/ssf-formula/pull/123'
-            # yamllint enable rule:line-length
+            # yamllint disable rule:line-length rule:quoted-strings
+            title: "ci(kitchen): avoid using bootstrap for '`'master'`' instances"
+            body: '* Automated using https://github.com/myii/ssf-formula/pull/124'
+            # yamllint enable rule:line-length rule:quoted-strings
           github:
             owner: 'saltstack-formulas'
             repo: ''

ssf/files/default/kitchen.yml

@@ -64,12 +64,12 @@ image: netmanagers/salt-{{ salt_ver }}-py{{ py_ver }}:{{ os | replace('/', '-')
 {#-         Need to look at if this can be resolved from within the formulas themselves, though                               #}
 {%-   filter indent(6) %}
 {%-     set prov_cmds = [] %}
-{#-     Specific to `master` or bootstrapped images #}
-{%-     if salt_ver == 'master' or not pre_salted %}
-{#-       Use the appropriate bootstrap options for pre-salted images vs. bootstrapped images #}
-{%-       set bootstrap_options = 'XdPbfrq' if pre_salted else 'XdPfq' %}
-{#-       Use the appropriate bootstrap method depending on the Salt version #}
-{%-       set bootstrap_method = 'git' if salt_ver in ['master'] else 'stable' %}
+{#-     Specific to bootstrapped images #}
+{%-     if not pre_salted %}
+{#-       Use the appropriate bootstrap options for bootstrapped images #}
+{%-       set bootstrap_options = 'XdPfq' %}
+{#-       Use the appropriate bootstrap method #}
+{%-       set bootstrap_method = 'stable' %}
 {%-       do prov_cmds.append('- curl -o bootstrap-salt.sh -L https://bootstrap.saltstack.com') %}
 {%-       do prov_cmds.append('- sh bootstrap-salt.sh -{0} -x python{1} {2} {3}'.format(
               bootstrap_options, py_ver, bootstrap_method, salt_ver