pyln-testing: Fix BitcoinD fd leak

Author: s373nZ

contrib/pyln-testing/pyln/testing/fixtures.py

@@ -164,6 +164,13 @@ def bitcoind(directory, teardown_checks):
         bitcoind.proc.kill()
     bitcoind.proc.wait()
 
+    # Ensure file descriptors are not leaking.
+    for f in ["stdout_write", "stderr_write", "stdout_read", "stderr_read"]:
+        try:
+            getattr(bitcoind, f).close()
+        except Exception:
+            pass
+
 
 class TeardownErrors(object):
     def __init__(self):