mark test flakey

Summary: I saw it fail returning a newline on the read

Reviewed By: @paulbiss

Differential Revision: D1577555
EZC: clear EG(exception) on return from zend_wrap_func()

Summary: Otherwise, if the exception is caught and then control is returned into
a zend_call_function() call which wrapped the throwing function, then
zend_call_function() will erroneously rethrow the exception, even though
it has already been handled.

https://bugzilla.wikimedia.org/show_bug.cgi?id=71174
Closes https://github.com/facebook/hhvm/pull/3834

Reviewed By: @ptarjan

Differential Revision: D1574411