[backend] in case of error the output is in e.output
    
    addressing:
    Traceback (most recent call last):
      File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
        self.run()
      File "/usr/share/copr/backend/dispatcher.py", line 313, in run
        ip = self.spawn_instance()
      File "/usr/share/copr/backend/dispatcher.py", line 168, in spawn_instance
        sys.stderr.write("%s\n" % result)
    UnboundLocalError: local variable 'result' referenced before assignment
    Process worker-builder:
    Traceback (most recent call last):
      File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
        self.run()
      File "/usr/share/copr/backend/dispatcher.py", line 313, in run
        ip = self.spawn_instance()
      File "/usr/share/copr/backend/dispatcher.py", line 168, in spawn_instance
        sys.stderr.write("%s\n" % result)
    UnboundLocalError: local variable 'result' referenced before assignment
    Process worker-builder:
    Traceback (most recent call last):
      File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
        self.run()
      File "/usr/share/copr/backend/dispatcher.py", line 313, in run
        ip = self.spawn_instance()
      File "/usr/share/copr/backend/dispatcher.py", line 168, in spawn_instance
        sys.stderr.write("%s\n" % result)
    UnboundLocalError: local variable 'result' referenced before assignment
    Process worker-builder:
    Traceback (most recent call last):
      File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
        self.run()
      File "/usr/share/copr/backend/dispatcher.py", line 313, in run
        ip = self.spawn_instance()
      File "/usr/share/copr/backend/dispatcher.py", line 168, in spawn_instance
        sys.stderr.write("%s\n" % result)
    UnboundLocalError: local variable 'result' referenced before assignment
    Traceback (most recent call last):
      File "/usr/share/copr/copr-be.py", line 306, in <module>
    Terminating on signal 15
        main(sys.argv[1:])
      File "/usr/share/copr/copr-be.py", line 297, in main
        cbe.run()
      File "/usr/share/copr/copr-be.py", line 240, in run
        raise errors.CoprBackendError, "Worker died unexpectedly, exiting"
    backend.errors.CoprBackendError: Worker died unexpectedly, exiting
    close failed in file object destructor:
    sys.excepthook is missing