Bug 1565243 - Support TC_OWNER without email address in taskgraph, r=jcj

Differential Revision: https://phabricator.services.mozilla.com/D37735

--HG--
extra : moz-landing-system : lando

.taskcluster.yml

@@ -55,7 +55,7 @@ tasks:
         image: djmitche/nss-decision:0.0.3
 
         env:
-          TC_OWNER: "${push.owner}"
+          TC_OWNER: "${ownerEmail}"
           TC_SOURCE: "${repository.url}"
           TC_PROJECT: ${repository.project}
           TC_SCHEDULER_ID: "${schedulerId}"