patch 8.1.1588: in :let-heredoc line continuation is recognized commit https://github.com/vim/vim/commit/e96a2498f9a2d3e93ac07431f6d4afd77f30afdf Author: Bram Moolenaar <Bram@vim.org> Date: Tue Jun 25 04:12:16 2019 +0200 patch 8.1.1588: in :let-heredoc line continuation is recognized Problem: In :let-heredoc line continuation is recognized. Solution: Do not consume line continuation. (Ozaki Kiichi, closes https://github.com/vim/vim/issues/4580)

--- a/src/testdir/test_let.vim
+++ b/src/testdir/test_let.vim
@@ -237,6 +237,14 @@ END
   END
   call assert_equal(['something', 'endfunc'], var1)
 
+  " not concatenate lines
+  let var1 =<< END
+some
+  \thing
+  \ else
+END
+  call assert_equal(['some', '  \thing', '  \ else'], var1)
+
   " ignore "python << xx"
   let var1 =<<END
 something