bpo-35721: Close socket pair if Popen in _UnixSubprocessTransport fails (GH-11553)
This slightly expands an existing test case `test_popen_error` to trigger a `ResourceWarning` and fixes it.
https://bugs.python.org/issue35721
diff --git a/Misc/ACKS b/Misc/ACKS
index 8b32325..77f1990 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -486,6 +486,7 @@
John Feuerstein
Carl Feynman
Vincent Fiack
+Niklas Fiekas
Anastasia Filatova
Tomer Filiba
Segev Finer
diff --git a/Misc/NEWS.d/next/Library/2019-01-18-16-23-00.bpo-35721.d8djAJ.rst b/Misc/NEWS.d/next/Library/2019-01-18-16-23-00.bpo-35721.d8djAJ.rst
new file mode 100644
index 0000000..5af4b1b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-01-18-16-23-00.bpo-35721.d8djAJ.rst
@@ -0,0 +1,3 @@
+Fix :meth:`asyncio.SelectorEventLoop.subprocess_exec()` leaks file descriptors
+if ``Popen`` fails and called with ``stdin=subprocess.PIPE``.
+Patch by Niklas Fiekas.