Fix #1603 (traceback on adding multiple books from directories, each directory single book with multiple versions)

src/calibre/library/database.py

@@ -1551,9 +1551,6 @@ def import_book_directory(self, dirpath, callback=None):
             
 
 
-    def has_book(self, mi):
-        return bool(self.conn.get('SELECT id FROM books where title=?', (mi.title,), all=False))
-
     def has_id(self, id):
         return self.conn.get('SELECT id FROM books where id=?', (id,), all=False) is not None
 

src/calibre/library/database2.py

@@ -561,7 +561,15 @@ def cover(self, index, index_is_id=False, as_file=False, as_image=False):
                 img.loadFromData(f.read())
                 return img
             return f if as_file else f.read()
-        
+    
+    def has_book(self, mi):
+        title = mi.title
+        if title:
+            if not isinstance(title, unicode):
+                title = title.decode(preferred_encoding, 'replace')
+            return bool(self.conn.get('SELECT id FROM books where title=?', (title,), all=False))
+        return False
+    
     def has_cover(self, index, index_is_id=False):
         id = index if  index_is_id else self.id(index)
         path = os.path.join(self.library_path, self.path(id, index_is_id=True), 'cover.jpg')