[MERGE] Make read() errors on directories raise ReadError not IO errors.

[Aaron Bentley]

Aaron Bentley has voted +1 (conditional).
Status is now: Conditionally approved
Comment:
With the Paramiko version, I don't understand why you're introducing 
this raise_on_failure boolean, instead of just passing LateReadError as 
failure_exc.  Otherwise, looks reasonable.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C1183538469.15211.75.camel%40localhost.localdomain%3E