Fix broken markdown output when attachment does not exist

wiki/plugins/attachments/markdown_extensions.py

@@ -59,7 +59,8 @@ class AttachmentPreprocessor(markdown.preprocessors.Preprocessor):
                         }))
                     line = self.markdown.htmlStash.store(html, safe=True)
                 except models.Attachment.DoesNotExist:
-                    line = line.replace(m.group(1), """<span class="attachment attachment-deleted">Attachment with ID #%s is deleted.</span>""" % attachment_id)
+                    html = """<span class="attachment attachment-deleted">Attachment with ID #%s is deleted.</span>""" % attachment_id
+                    line = line.replace(m.group(2), self.markdown.htmlStash.store(html, safe=True))
                 line = before + line + after
             new_text.append(line)
         return new_text