plug memory leak in book identifiers.

diff --git a/lily/book.cc b/lily/book.cc
index f307bcf3c31c830a1523f29788c828c71ef6bece..e9f2e3ea2ffdb7416ebac4c1f5178f2629505353 100644 (file)
--- a/lily/book.cc
+++ b/lily/book.cc
@@ -46,13 +46,17 @@ Book::Book (Book const &s)
   smobify_self ();
 
   if (s.paper_)
-    paper_ = s.paper_->clone ();
+    {
+      paper_ = s.paper_->clone ();
+      paper_->unprotect ();
+    }
   
   input_location_ = make_input (*s.origin ());
+
   header_ = ly_make_anonymous_module (false);
   if (ly_is_module (s.header_))
     ly_module_copy (header_, s.header_);
-
+  
   SCM *t = &scores_;
   for (SCM p = s.scores_; scm_is_pair (p); p = scm_cdr (p))
     {