Initial work on a UI for yanking releases

warehouse/static/sass/blocks/_callout-block.scss

@@ -73,6 +73,27 @@
     }
   }
 
+  &--warn {
+    border-color: $warn-color;
+
+    > :not(.modal):not(.button) {
+      color: $warn-text;
+
+      a:not(.button) {
+        color: $warn-text;
+        text-decoration: underline;
+
+        &:hover {
+          color: darken($warn-text, 4);
+        }
+      }
+    }
+
+    &:before {
+      background-color: $warn-color;
+    }
+  }
+
   &--success {
     border-color: $success-color;
 

warehouse/templates/manage/release.html

@@ -115,6 +115,15 @@ <h3>No files found</h3>
 
   <h3>Release settings</h3>
 
+  <div class="callout-block callout-block--warn">
+    <h3>Yank release</h3>
+    <p>
+      Yanking will mark this release{% if files %}, and {{ files|length() }} {% trans count=files|length %}file{% pluralize %}files{% endtrans %}{% endif %}
+      to be ignored when installing in most common scenarios, except when being
+      installed as a pinned release.
+    </p>
+  </div>
+
   <div class="callout-block callout-block--danger">
     <h3>Delete release</h3>
     <p>
@@ -130,7 +139,7 @@ <h3>Delete release</h3>
       Deleting will irreversibly delete this release.
     {% endif %}
       You will not be able to re-upload a new distribution of the same type with the same version number.
-      Consider making a new release or a <a href="https://www.python.org/dev/peps/pep-0440/#post-releases">post release</a> instead.
+      Consider yanking this release, making a new release, or a <a href="https://www.python.org/dev/peps/pep-0440/#post-releases">post release</a> instead.
     </p>
     {{ confirm_button("Delete release", "Version", release.version) }}
   </div>