[devhelp] Fix warning when book cannot be read

[Aleksander Morgado <aleksm src gnome org>]

commit e462dd85ceaf23e504f32090e1fc62112668cb94
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun Mar 22 11:23:40 2015 -0500

    Fix warning when book cannot be read
    
    priv->path is always NULL at this point
    
    https://bugzilla.gnome.org/show_bug.cgi?id=746609

 src/dh-book.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/dh-book.c b/src/dh-book.c
index 1e4999b..d3da2ef 100644
--- a/src/dh-book.c
+++ b/src/dh-book.c
@@ -219,7 +219,7 @@ dh_book_new (const gchar *book_path)
                                    &priv->keywords,
                                    &error)) {
                 g_warning ("Failed to read '%s': %s",
-                           priv->path, error->message);
+                           book_path, error->message);
                 g_error_free (error);
 
                 /* Deallocate the book, as we are not going to add it