boto/boto — pull request #1175 by jamesls (2012-12-11 01:31:51+00:00)
Title: Add debug logging for credential location

This makes it easier to troubleshoot any credential
issues. Only the location of the credentials is logged,
not the actual credentials themselves.

Example:

```
>>> import os
>>> import boto
>>> boto.set_stream_logger('boto')
>>> c = boto.connect_s3()
2012-12-10 17:26:13,607 boto [DEBUG]:Using access key found in config file.
2012-12-10 17:26:13,607 boto [DEBUG]:Using secret key found in config file.

>>> c = boto.connect_s3('access_key', 'secret_key')
2012-12-10 17:26:23,071 boto [DEBUG]:Using access key provided by client.
2012-12-10 17:26:23,071 boto [DEBUG]:Using secret key provided by client.

>>> os.environ['AWS_ACCESS_KEY_ID'] = 'environ_access_key'
>>> os.environ['AWS_SECRET_ACCESS_KEY'] = 'environ_secret_key'
>>> c = boto.connect_s3()
2012-12-10 17:27:04,428 boto [DEBUG]:Using access key found in environment variable.
2012-12-10 17:27:04,429 boto [DEBUG]:Using secret key found in environment variable.
```

Would anyone else find this useful?