Simplifies test if binary mode.

pubs/content.py

@@ -50,10 +50,10 @@ def system_path(path):
 
 
 def _open(path, mode):
-        if mode.find('b') == -1:
-            return open(system_path(path), mode, encoding='utf-8')
-        else:
-            return open(system_path(path), mode)
+    if 'b' in mode:
+        return open(system_path(path), mode, encoding='utf-8')
+    else:
+        return open(system_path(path), mode)
 
 
 def check_file(path, fail=True):