settings: Display 'rebase-merge' option in VCS settings.

rhodecode/templates/base/vcs_settings.html

@@ -213,4 +213,23 b''
             </div>
         </div>
     % endif
+
+    ## This condition has to be adapted if we add more labs settings for
+    ## VCS types other than 'hg'
+    % if c.labs_active and (display_globals or repo_type in ['hg']):
+        <div class="panel panel-danger">
+            <div class="panel-heading">
+                <h3 class="panel-title">${_('Labs settings')}</h3>
+            </div>
+            <div class="panel-body">
+                <div class="checkbox">
+                    ${h.checkbox('rhodecode_hg_use_rebase_for_merging' + suffix, 'True', **kwargs)}
+                    <label for="rhodecode_hg_use_rebase_for_merging${suffix}">${_('Mercurial server-side merge')}</label>
+                </div>
+                <div class="label">
+                    <span class="help-block">${_('Use rebase instead of creating a merge commit when merging via web interface')}</span>
+                </div>
+            </div>
+        </div>
+    % endif
 </%def>