Add separator between date and patchset in change log

Change-Id: Id8321bb7b088416dc2748e7fdea5e1eea75a833e
diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts b/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts
index b93040b..8d03e32 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message_html.ts
@@ -305,7 +305,7 @@
           </gr-button>
         </template>
         <template is="dom-if" if="[[message._revision_number]]">
-          <span class="patchset">[[message._revision_number]]</span>
+          <span class="patchset">[[message._revision_number]] |</span>
         </template>
         <template is="dom-if" if="[[!message.id]]">
           <span class="date">