diff -r dda25c37d02b Lib/test/test_posix.py
--- a/Lib/test/test_posix.py	Sat Aug 13 14:47:54 2016 -0400
+++ b/Lib/test/test_posix.py	Thu Aug 18 20:08:36 2016 -0400
@@ -799,7 +799,11 @@
             groups = idg.read().strip()
             ret = idg.close()
 
-        if ret is not None or not groups:
+        try:
+            idg_groups = set(int(g) for g in groups.split())
+        except ValueError:
+            idg_groups = set()
+        if ret is not None or not idg_groups:
             raise unittest.SkipTest("need working 'id -G'")
 
         # Issues 16698: OS X ABIs prior to 10.6 have limits on getgroups()
@@ -809,13 +813,19 @@
             if tuple(int(n) for n in dt.split('.')[0:2]) < (10, 6):
                 raise unittest.SkipTest("getgroups(2) is broken prior to 10.6")
 
+        posix_groups = set(posix.getgroups())
+        # #10822/#26944 - it is implementation defined whether
+        # posix.getgroups() and the 'id -G' command include the effective gid,
+        # so we eliminate it from the match sets.
+        egid = posix.getegid()
+        if egid in idg_groups:
+            idg_groups.remove(egid)
+        if egid in posix_groups:
+            posix_groups.remove(egid)
+
         # 'id -G' and 'os.getgroups()' should return the same
-        # groups, ignoring order and duplicates.
-        # #10822 - it is implementation defined whether posix.getgroups()
-        # includes the effective gid so we include it anyway, since id -G does
-        self.assertEqual(
-                set([int(x) for x in groups.split()]),
-                set(posix.getgroups() + [posix.getegid()]))
+        # groups, ignoring order, duplicates, and the egid.
+        self.assertEqual(idg_groups, posix_groups)
 
     # tests for the posix *at functions follow