handles the BrokenPipeError

[christophkloeffel]

fixes #94

[phiwuu]

While reviewing this I tried to figure out what exactly the "default behavior" is. The documentation is very nebulous about it. On the one hand, whatever the behavior is, it probably solves #94.
On the other hand, https://docs.python.org/3/library/signal.html#note-on-sigpipe recommends that one should not use SIG_DFL in this very scenario we have at hand here.

In order to come to a conclusion, we have to decide the following: What is the expected return code? Should we call sys.exit(1) or sys.exit(0) in a scenario where we run into BrokenPipeError?

See my comment in the related issue: #94 (comment)

[christophkloeffel]

By default, Python catches the SIGPIPE signal and raises a BrokenPipeError when it occurs. The signal.signal(signal.SIGPIPE, signal.SIG_DFL) line restores the default operating system behaviour for SIGPIPE, which is to terminate the program without raising an error. This is useful in cases like piping output to head, where you expect the pipe to be closed, and you don't want an error to be printed.

For my understanding Python is not executing the default behaviour of this signal https://docs.python.org/3/library/signal.html#signal.SIGPIPE, so I explicitly tell Python to do so. And not raise an Error.

[christophkloeffel]

https://docs.python.org/3/library/signal.html#note-on-sigpipe using the exception handling provided as an example,
I now return 141 explicitly in case of a BrokenPipeError