bpo-28334: netrc() now uses expanduser() to find .netrc file (GH-4537)

Previously, netrc.netrc() was raised an exception if $HOME is not set.

Authored-By: Dimitri Merejkowsky <dimitri.merejkowsky@tanker.io>
diff --git a/Misc/ACKS b/Misc/ACKS
index 0511390..fc7154f 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1031,6 +1031,7 @@
 Lucas Prado Melo
 Ezio Melotti
 Doug Mennella
+Dimitri Merejkowsky
 Brian Merrell
 Alexis Métaireau
 Luke Mewburn
diff --git a/Misc/NEWS.d/next/Library/2017-11-24-11-50-41.bpo-28334.3gGGlt.rst b/Misc/NEWS.d/next/Library/2017-11-24-11-50-41.bpo-28334.3gGGlt.rst
new file mode 100644
index 0000000..074036b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-11-24-11-50-41.bpo-28334.3gGGlt.rst
@@ -0,0 +1,3 @@
+Use :func:`os.path.expanduser` to find the ``~/.netrc`` file in
+:class:`netrc.netrc`.  If it does not exist, :exc:`FileNotFoundError`
+is raised.  Patch by Dimitri Merejkowsky.