Add regtest for issue 1440

diff --git a/input/regression/book-label-no-segfault.ly b/input/regression/book-label-no-segfault.ly
new file mode 100644 (file)
index 0000000..f8ca155
--- /dev/null
+++ b/input/regression/book-label-no-segfault.ly
@@ -0,0 +1,9 @@
+\version "2.13.43"
+
+\header {
+  texidoc = "
+A book(part) can contain only a label without causing a segfault.
+"
+}
+
+\book { \label #'foo }