When running test cases in the debugger it spits out resource warnings
about non-closed streams [1]. Explicitly closing the streams of the
subprocesses and log streamer fixes this warning. Maybe this even
solves the memory leak we're currently seeing in the executors.
[1] Trace:
/zuul/executor/server.py:1894: ResourceWarning: unclosed file <_io.BufferedReader name=60>
self.proc = None
ResourceWarning: Enable tracemalloc to get the object allocation traceback
/zuul/executor/server.py:124: ResourceWarning: unclosed file <_io.BufferedReader name=11>
stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
ResourceWarning: Enable tracemalloc to get the object allocation traceback
Change-Id: I65f191dc2e50f9c84f5bf6a3967d768d7ebe6b04
3d9f47be1d