#775964: skip YP/NIS entries instead of failing the test

Also includes doc updates mentioning that these entries may not
be retrievable via getgrnam and getgrgid.

Patch by Bobby Impollonia.
diff --git a/Misc/NEWS b/Misc/NEWS
index 981b53f..2b6c78c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -38,6 +38,13 @@
   or otherwise not wait for exiting child processes.
 
 
+Tests
+-----
+
+- Issue #775964: test_grp now skips YP/NIS entries instead of failing when
+  encountering them.
+
+
 What's New in Python 3.2 Beta 1?
 ================================