patch 9.1.1145: multi-line completion has wrong indentation for last line

Problem:  When expanding omni completion items with newlines (e.g.
          `then\n\t\nend`), the end statement gets wrong indentation.
Solution: Add OPENLINE_FORCE_INDENT flag to make open_line() use
          second_line_indent directly (glepnir)

closes: #16614

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Justin M. Keyes <justinkz@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index 63f0016..82d2ef0 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -1946,6 +1946,23 @@
   call VerifyScreenDump(buf, 'Test_pum_with_special_characters_08', {})
   call term_sendkeys(buf, "\<C-E>\<Esc>")
 
+  call term_sendkeys(buf, ":setlocal autoindent tabstop=2 shiftwidth=2\<CR>")
+  call term_sendkeys(buf, "Slocal a = \<C-X>\<C-O>")
+  call TermWait(buf, 50)
+  call VerifyScreenDump(buf, 'Test_pum_with_special_characters_09', {})
+
+  call term_sendkeys(buf, "\<C-Y>")
+  call TermWait(buf, 50)
+  call VerifyScreenDump(buf, 'Test_pum_with_special_characters_10', {})
+
+  call term_sendkeys(buf, "\<ESC>kAlocal b = \<C-X>\<C-O>")
+  call TermWait(buf, 50)
+  call VerifyScreenDump(buf, 'Test_pum_with_special_characters_11', {})
+
+  call term_sendkeys(buf, "\<C-Y>")
+  call TermWait(buf, 50)
+  call VerifyScreenDump(buf, 'Test_pum_with_special_characters_12', {})
+
   call StopVimInTerminal(buf)
 endfunc