This patches add compatibility for the forthcoming RobotFramework 5.

Taken from: https://github.com/robotframework/SSHLibrary/pull/403.
diff --git a/src/SSHLibrary/pythonforward.py b/src/SSHLibrary/pythonforward.py
index 8b85997b7..607985cf4 100644
--- a/src/SSHLibrary/pythonforward.py
+++ b/src/SSHLibrary/pythonforward.py
@@ -1,9 +1,9 @@
 import select
 import socket
 import threading
-from robot.utils import platform
+from robot.utils import PY2, WINDOWS
 from .logger import logger
-if platform.PY2 and platform.WINDOWS:
+if PY2 and WINDOWS:
     import win_inet_pton
 try:
     import SocketServer
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<div class='path'>path: <a href='/guix/log/?id=89da127035737bdf922bc566970c5506c2e01b00'>root</a>/<a href='/guix/log/gnu?id=89da127035737bdf922bc566970c5506c2e01b00'>gnu</a>/<a href='/guix/log/gnu/packages?id=89da127035737bdf922bc566970c5506c2e01b00'>packages</a>/<a href='/guix/log/gnu/packages/pth.scm?id=89da127035737bdf922bc566970c5506c2e01b00'>pth.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/pth.scm?id=89da127035737bdf922bc566970c5506c2e01b00&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2017-03-30 22:59:53 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/pth.scm?id=84157bb8bf2c610584e0836047da4c710f8eaf76'>Merge branch 'master' into core-updates</a><span class='msg-avail'>...<span class='msg-tooltip'>Most conflicts are from 6fd52309b8f52c9bb59fccffac53e029ce94b698.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2017-03-30 01:30:16 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/pth.scm?id=6fd52309b8f52c9bb59fccffac53e029ce94b698'>gnu: Use HTTPS for almost all gnu.org HOME-PAGEs.</a><span class='msg-avail'>...<span class='msg-tooltip'>All HTTP gnu.org (and supported subdomain) HOME-PAGEs changed to HTTPS.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-03-02 11:51:43 +0200'>2017-03-02</span></td><td><a href='/guix/commit/gnu/packages/pth.scm?id=10045e5c81b6dfcf3804ceb1bb4b8df04bde7c98'>gnu: pth: Add support for aarch64.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/pth.scm (pth)[arguments]: When compiling on aarch64 add
the '--host=aarch64' flag.
[home-page]: Use https.
</span></span></td><td>Efraim Flashner</td></tr>