Check that limit is initialized and is > 0 before raising log length limit exceptions
Check that limit is initialized and is > 0 before raising log length limit exceptions

Buffer#<< is called asynchronously by a separate thread Net::SSH is using. Buffer#initialize may or may not happen by then.
This causes build to be immediately terminated w/o log output some of the time, exactly what people have been reporting
for the last day or so.

As a side note, previous implementation used one condition and 2 methods in the output callback. Log length was initialized
before SSH session was started. Now we have a String subclass, super.tap, lazy config initialization and exceptions.
Maybe movign back to the previous approach will make things easier to reason about?

gavioto/travis-worker,gavioto/travis-worker,ireznice/travis-worker,final-ci/travis-worker,travis-ci/travis-worker,ireznice/travis-worker,travis-ci/travis-worker,final-ci/travis-worker