check-code: disallow use of hasattr() The hasattr() builtin from Python < 3.2 [1] has slightly surprising behavior: it catches all exceptions, even KeyboardInterrupt. This causes it to have several surprising side effects, such as hiding warnings that occur during attribute load and causing mysterious failure modes when ^Cing an application. In later versions of Python 2.x [0], exception classes which do not inherit from Exception (such as SystemExit and KeyboardInterrupt) are not caught, but other types of exceptions may still silently cause returning False instead of getting a reasonable exception. [0] http://bugs.python.org/issue2196 [1] http://docs.python.org/dev/whatsnew/3.2.html