Without the patch the debian build stops due to a compiler error.
The compiler stops because of the -Werror=format-security option set.
This should be fixed upstream.
--- a/tests/output/render-test.c
+++ b/tests/output/render-test.c
@@ -488,7 +488,7 @@
                   tab_joint_text (tab, c, r, c + cs - 1, r + rs - 1, opt,
                                   content);
                 else
-                  tab_footnote (tab, c, r, content);
+                  tab_footnote (tab, c, r, "%s", content);
             }
         }