Python: catch narrower exception types

[chrisjbillington]

Catch Exception, instead of BaseException or using bare except: clauses.

This is still very broad, but avoids the case of catching SystemExit or KeyboardInterrupt (which are not subclasses of Exception) and re-raising them as ConnectionError.

Application code may handle ConnectionErrors differently (such as attempting re-connection) to SystemExit or KeyboardInterrupt, which may be raised in signal handlers and which the application may treat as a relatively normal shutdown.

[tvanderbruggen]

Makes sense. Thanks.