This gives an uncaught `TypeError` with Python `2.7.5` for me:

```bash
...
File "/Users/taylordt/Projects/Amazon/boto/boto/utils.py", line 309, in __getitem__
    boto.log.error("Caught exception reading meta data for the '%s' try" % i+1)
TypeError: cannot concatenate 'str' and 'int' objects
-------------------- >> begin captured logging << --------------------
boto: DEBUG: encountered 'JSONDecodeError' exception: Expecting property name: line 1 column 30 (char 30)
boto: DEBUG: corrupted JSON data found: {"invalid_json_format" : true,}
--------------------- >> end captured logging << ---------------------

----------------------------------------------------------------------
Ran 573 tests in 1.918s

FAILED (SKIP=1, errors=2)
```

The `%` operator is getting precedence over the addition operator and so you are formatting the string, then trying to add the full string with an integer. This seems to fix it:

```python
boto.log.error("Caught exception reading meta data for the '%s' try" % (i + 1))
```