shorten filename by os.path.basename in guess_filename(obj)

requests/utils.py

@@ -89,7 +89,7 @@ def guess_filename(obj):
     """Tries to guess the filename of the given object."""
     name = getattr(obj, 'name', None)
     if name and name[0] != '<' and name[-1] != '>':
-        return name
+        return os.path.basename(name)
 
 
 def from_key_val_list(value):