fix(init): properly support github-release variables in .tc.yml template (#449)

Author: ahal

template/{{cookiecutter.project_name}}/taskcluster.github.yml

@@ -16,48 +16,53 @@ tasks:
           ownerEmail:
               $switch:
                   'tasks_for == "github-push"': '${event.pusher.email}'
+                  'tasks_for == "github-release"': '${event.sender.login}@users.noreply.github.com'
                   'tasks_for[:19] == "github-pull-request"': '${event.pull_request.user.login}@users.noreply.github.com'
                   'tasks_for in ["cron", "action"]': '${tasks_for}@noreply.mozilla.org'
           baseRepoUrl:
               $switch:
-                  'tasks_for == "github-push"': '${event.repository.html_url}'
                   'tasks_for[:19] == "github-pull-request"': '${event.pull_request.base.repo.html_url}'
                   'tasks_for in ["cron", "action"]': '${repository.url}'
+                  $default: '${event.repository.html_url}'
           repoUrl:
               $switch:
-                  'tasks_for == "github-push"': '${event.repository.html_url}'
                   'tasks_for[:19] == "github-pull-request"': '${event.pull_request.head.repo.html_url}'
                   'tasks_for in ["cron", "action"]': '${repository.url}'
+                  $default: '${event.repository.html_url}'
           project:
               $switch:
-                  'tasks_for == "github-push"': '${event.repository.name}'
+                  'tasks_for in ["github-push", "github-release"]': '${event.repository.name}'
                   'tasks_for[:19] == "github-pull-request"': '${event.pull_request.head.repo.name}'
                   'tasks_for in ["cron", "action"]': '${repository.project}'
           head_branch:
               $switch:
                   'tasks_for[:19] == "github-pull-request"': ${event.pull_request.head.ref}
                   'tasks_for == "github-push"': ${event.ref}
                   'tasks_for == "github-release"': '${event.release.target_commitish}'
-                  'tasks_for in ["action", "cron"]': '${push.branch}'
+                  'tasks_for in ["cron", "action"]': '${push.branch}'
           base_ref:
               $switch:
                   'tasks_for[:19] == "github-pull-request"': ${event.pull_request.base.ref}
                   'tasks_for == "github-push" && event.base_ref': ${event.base_ref}
                   'tasks_for == "github-push"': ${event.ref}
+                  'tasks_for == "github-release"': ${event.release.tag_name}
                   'tasks_for in ["cron", "action"]': '${push.branch}'
           head_ref:
               $switch:
                   'tasks_for[:19] == "github-pull-request"': ${event.pull_request.head.ref}
                   'tasks_for == "github-push"': ${event.ref}
+                  'tasks_for == "github-release"': ${event.release.tag_name}
                   'tasks_for in ["cron", "action"]': '${push.branch}'
           base_sha:
               $switch:
                   'tasks_for == "github-push"': '${event.before}'
+                  'tasks_for == "github-release"': '${event.release.target_commitish}'
                   'tasks_for[:19] == "github-pull-request"': '${event.pull_request.base.sha}'
                   'tasks_for in ["cron", "action"]': '${push.revision}'
           head_sha:
               $switch:
                   'tasks_for == "github-push"': '${event.after}'
+                  'tasks_for == "github-release"': '${event.release.tag_name}'
                   'tasks_for[:19] == "github-pull-request"': '${event.pull_request.head.sha}'
                   'tasks_for in ["cron", "action"]': '${push.revision}'
           ownTaskId:
@@ -68,18 +73,24 @@ tasks:
               $switch:
                   'tasks_for[:19] == "github-pull-request"': ${event.action}
                   $default: 'UNDEFINED'
+          releaseAction:
+              $if: 'tasks_for == "github-release"'
+              then: ${event.action}
+              else: 'UNDEFINED'
           isPullRequest:
               $eval: 'tasks_for[:19] == "github-pull-request"'
       in:
           $let:
               short_base_ref:
-                  $if: 'base_ref[:11] == "refs/heads/"'
-                  then: {$eval: 'base_ref[11:]'}
-                  else: ${base_ref}
+                  $switch:
+                      'base_ref[:10] == "refs/tags/"': '${base_ref[10:]}'
+                      'base_ref[:11] == "refs/heads/"': '${$base_ref[11:]}'
+                      $default: '${base_ref}'
               short_head_ref:
-                  $if: 'head_ref[:11] == "refs/heads/"'
-                  then: {$eval: 'head_ref[11:]'}
-                  else: ${head_ref}
+                  $switch:
+                      'head_ref[:10] == "refs/tags/"': '${head_ref[10:]}'
+                      'head_ref[:11] == "refs/heads/"': '${head_ref[11:]}'
+                      $default: '${head_ref}'
           in:
               $if: >
                   tasks_for in ["action", "cron"]