patch 8.2.3687: blockwise insert does not handle autoindent properly

Problem:    Blockwise insert does not handle autoindent properly when tab is
            inserted.
Solution:   Adjust text column for indent before computing column.
            (closes #9229)
diff --git a/src/testdir/test_blockedit.vim b/src/testdir/test_blockedit.vim
index 216238a..e95520f 100644
--- a/src/testdir/test_blockedit.vim
+++ b/src/testdir/test_blockedit.vim
@@ -37,6 +37,31 @@
   END
   call assert_equal(expected, getline(1, 5))
 
+  " insert on the next column should do exactly the same
+  :%dele
+  call setline(1, lines)
+  exe "norm! 2Gf)l\<c-v>2jI: asdf\<esc>"
+  call assert_equal(expected, getline(1, 5))
+
+  :%dele
+  call setline(1, lines)
+  setlocal sw=8 noet
+  exe "norm! 2Gf)\<c-v>2jA: asdf\<esc>"
+  let expected =<< trim END
+      var d = {
+      	a: (): asdf => 0,
+      b: (): asdf => 0,
+      c: (): asdf => 0,
+      }
+  END
+  call assert_equal(expected, getline(1, 5))
+
+  " insert on the next column should do exactly the same
+  :%dele
+  call setline(1, lines)
+  exe "norm! 2Gf)l\<c-v>2jI: asdf\<esc>"
+  call assert_equal(expected, getline(1, 5))
+
   filetype off
   bwipe!
 endfunc