Improve container cleanup to handle short image IDs and running containers

- Match both short (12 char) and long image IDs
- Check container state before stopping to avoid unnecessary operations
- Handle NotModifiedError when container is already stopped
- Fixes CI failure where running containers prevented image removal

Author: chorrell

spec/spec_helper.rb

@@ -17,9 +17,15 @@ def delete_image
     puts "Deleting image..."
     # Stop and remove only containers created from this image
     Docker::Container.all(:all => true).each do |container|
-      if container.info['Image'] == @image.id || container.info['ImageID'] == @image.id
-        container.stop
-        container.delete(:force => true)
+      image_id = container.info['Image']
+      # Match both short and long image IDs
+      if image_id == @image.id || image_id == @image.id[0..11] || container.info['ImageID'] == @image.id
+        begin
+          container.stop unless container.info['State'] == 'exited'
+          container.delete(:force => true)
+        rescue Docker::Error::NotModifiedError
+          # Container already stopped, ignore
+        end
       end
     end