koji: add scm plugin

Add a scm plugin and some policy for it.

Signed-off-by: Kevin Fenzi <kevin@scrye.com>

roles/koji_builder/templates/kojid.conf

@@ -163,6 +163,7 @@ keytab = /etc/kojid/kojid.keytab
 {{ plugins.append("osbuild") }}
 {% endif %}
 
+{{ plugins.append("scmpolicy") }}
 
 ; Config for the runroot plugin lives in /etc/kojid/runroot.conf, if enabled
 plugins = {{ plugins | join(" ") }}

roles/koji_hub/templates/hub.conf.j2

@@ -211,3 +211,9 @@ build_from_scm =
     # allow to build from forks
     match scm_type GIT GIT+SSH && match scm_host src.fedoraproject.org/forks/* :: allow
 {% endif %}
+
+scm =
+      # allow scratch builds from any commits
+      bool scratch :: allow
+      match_all branches * !! deny Commit must be present on some branch
+      all :: allow