compare: fixed spacing for common compare commit in PR open compare page.

rhodecode/public/css/main.less

@@ -1478,8 +1478,7 b' table.integrations {'
 }
 
 div.ancestor {
-    margin: @padding 0;
-    line-height: 3.0em;
+    margin: -30px 0px;
 }
 
 .cs_icon_td input[type="checkbox"] {

rhodecode/templates/compare/compare_commits.html

@@ -3,11 +3,9 b''
 
 %if c.ancestor:
 <div class="ancestor">${_('Common Ancestor Commit')}:
-    <a href="${h.url('changeset_home',
-                     repo_name=c.repo_name,
-                     revision=c.ancestor)}">
+    <a href="${h.url('changeset_home', repo_name=c.repo_name, revision=c.ancestor)}">
         ${h.short_id(c.ancestor)}
-    </a>
+    </a>. ${_('Compare was calculated based on this shared commit.')}
 </div>
 %endif