fix pass None to tob (#1018)

1 files changed, 1 insertions, 1 deletions

diff --git a/bottle.py b/bottle.py
index c556baf..e75944c 100755
--- a/bottle.py
+++ b/bottle.py
@@ -161,7 +161,7 @@ else:  # 2.x
 def tob(s, enc='utf8'):
     if isinstance(s, unicode):
         return s.encode(enc)
-    return bytes("" if s is None else s)
+    return b'' if s is None else bytes(s)
 
 
 def touni(s, enc='utf8', err='strict'):