See https://github.com/python/cpython/issues/115189

Author: Bill Sommerfeld <sommerfeld@hamachi.org>

diff -wpruN --no-dereference '--exclude=*.orig' a~/Lib/test/test_termios.py a/Lib/test/test_termios.py
--- a~/Lib/test/test_termios.py	1970-01-01 00:00:00
+++ a/Lib/test/test_termios.py	1970-01-01 00:00:00
@@ -16,6 +16,16 @@ class TestFunctions(unittest.TestCase):
 
     def setUp(self):
         self.master_fd, self.fd = os.openpty()
+        # some systems will not let you get the window size unless it's been
+        # set first, so try to set it if we can't get it
+        try:
+            termios.tcgetwinsize(self.fd)
+        except termios.error:
+            try:
+                termios.tcsetwinsize(self.fd, (24, 80))
+            except termios.error:
+                pass
+
         self.addCleanup(os.close, self.master_fd)
         self.stream = self.enterContext(open(self.fd, 'wb', buffering=0))
         tmp = self.enterContext(tempfile.TemporaryFile(mode='wb', buffering=0))
diff -wpruN --no-dereference '--exclude=*.orig' a~/Modules/termios.c a/Modules/termios.c
--- a~/Modules/termios.c	1970-01-01 00:00:00
+++ a/Modules/termios.c	1970-01-01 00:00:00
@@ -518,9 +518,12 @@ termios_tcsetwinsize_impl(PyObject *modu
 #if defined(TIOCGWINSZ) && defined(TIOCSWINSZ)
     struct winsize w;
     /* Get the old winsize because it might have
-       more fields such as xpixel, ypixel. */
+       more fields such as xpixel, ypixel, but keep going and
+       try to set it even if this fails since on some systems
+       on a new pty you can't get the winsize until it's been
+       set once. */
     if (ioctl(fd, TIOCGWINSZ, &w) == -1) {
-        return PyErr_SetFromErrno(state->TermiosError);
+	memset(&w, 0, sizeof(w));
     }
 
     w.ws_row = (unsigned short) winsz_0;