patch 8.2.0342: some code in ex_getln.c not covered by tests

Problem:    Some code in ex_getln.c not covered by tests.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5717)
diff --git a/src/testdir/test_iminsert.vim b/src/testdir/test_iminsert.vim
index fb2ef05..1880662 100644
--- a/src/testdir/test_iminsert.vim
+++ b/src/testdir/test_iminsert.vim
@@ -62,3 +62,5 @@
   set imactivatefunc=
   set imstatusfunc=
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab