[Minor] Fix legacy string values in modify headers routine

Issue: #4246

diff --git a/lualib/lua_mime.lua b/lualib/lua_mime.lua
index 02329badd65d58f00d788bb047c8a4bb75a88906..01a2fc95e1e050131193ed93fc65dcd8711bdcad 100644 (file)
--- a/lualib/lua_mime.lua
+++ b/lualib/lua_mime.lua
@@ -532,6 +532,8 @@ exports.modify_headers = function(task, hdr_alterations)
       for _,v in ipairs(hdr) do
         table.insert(add_tbl, {-1, v})
       end
+    elseif type(hdr) == 'string' then
+      table.insert(add_tbl, {-1, hdr})
     end
   end
   if hdr_alterations.order then