Fix short commit hash link

- Only relativize the commit link if the link does not start with a
  scheme.
- The link text now reflects the SHA-1 of the current revision rather
  than that of the latest revision.

Bug: Issue 4174
Change-Id: Ie66809ce951df6bb8b686bd7fa4ecb4328fb9d1d

polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.html

@@ -110,10 +110,10 @@ limitations under the License.
       <span class="value">
         <template is="dom-if" if="[[_showWebLink]]">
           <a target="_blank"
-              href$="[[_webLink]]">[[_computeShortHash(change)]]</a>
+              href$="[[_webLink]]">[[_computeShortHash(commitInfo)]]</a>
         </template>
         <template is="dom-if" if="[[!_showWebLink]]">
-          [[_computeShortHash(change)]]
+          [[_computeShortHash(commitInfo)]]
         </template>
       </span>
     </section>

polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.js

@@ -68,11 +68,16 @@
                 .replace('${commit}', commitInfo.commit);
       }
 
-      return '../../' + commitInfo.web_links[0].url;
+      var webLink = commitInfo.web_links[0].url;
+      if (!/^https?\:\/\//.test(webLink)) {
+        webLink = '../../' + webLink;
+      }
+
+      return webLink;
     },
 
-    _computeShortHash: function(change) {
-      return change.current_revision.slice(0, 7);
+    _computeShortHash: function(commitInfo) {
+      return commitInfo.commit.slice(0, 7);
     },
 
     _computeHideStrategy: function(change) {

polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata_test.html

@@ -87,6 +87,16 @@ limitations under the License.
           element.serverConfig), '../../link-url');
     });
 
+    test('does not relativize web links that begin with scheme', function() {
+      element.commitInfo = {web_links: [{url: 'https://link-url'}]};
+      element.serverConfig = {};
+
+      assert.isOk(element._computeShowWebLink(element.change,
+          element.commitInfo, element.serverConfig));
+      assert.equal(element._computeWebLink(element.change, element.commitInfo,
+          element.serverConfig), 'https://link-url');
+    });
+
     test('use gitweb when available', function() {
       element.commitInfo = {commit: 'commit-sha'};
       element.serverConfig = {gitweb: {