patch 7.4.834
Problem:    gettabvar() doesn't work after Vim start. (Szymon Wrozynski)
Solution:   Handle first window in tab still being NULL. (Christian Brabandt)
diff --git a/src/testdir/test91.ok b/src/testdir/test91.ok
index 809952b..62adec1 100644
--- a/src/testdir/test91.ok
+++ b/src/testdir/test91.ok
@@ -1,4 +1,6 @@
 start:
+'abcd'
+'abcd'
 '1234'
 '1234'
 {'var_num': '1234'}