fix(*): address broken tests

kong/router/atc.lua

@@ -445,7 +445,8 @@ function _M:exec(ctx)
   local fields = self.fields
 
   local req_uri = ctx and ctx.request_uri or var.request_uri
-  local req_host = lower(get_header("host", ctx))
+  local req_host = get_header("host", ctx)
+  req_host = req_host and lower(req_host) or nil
 
   req_uri = strip_uri_args(req_uri)
 

kong/router/traditional.lua

@@ -1755,10 +1755,12 @@ function _M.new(routes, cache, cache_neg)
     exec = function(ctx)
       local req_method = get_method()
       local req_uri = ctx and ctx.request_uri or var.request_uri
-      local req_host = lower(get_header("host", ctx))
+      local req_host = get_header("host", ctx)
       local req_scheme = ctx and ctx.scheme or var.scheme
       local sni = server_name()
 
+      req_host = req_host and lower(req_host) or nil
+
       local headers
       if match_headers then
         local err

spec/01-unit/08-router_spec.lua

@@ -164,7 +164,7 @@ for _, flavor in ipairs({ "traditional", "traditional_compatible", "expressions"
               hosts = {
                 "domain-1.org",
                 "domain-2.org",
-                "Domain-3.org"
+                "Domain-Capitalized.org"
               },
             },
           },
@@ -388,7 +388,7 @@ for _, flavor in ipairs({ "traditional", "traditional_compatible", "expressions"
 
       it("[host] matches should be case insensitive", function()
         -- host
-        local match_t = router:select("GET", "/", "domain-3.org")
+        local match_t = router:select("GET", "/", "domain-capitalized.org")
         assert.truthy(match_t)
         assert.same(use_case[1].route, match_t.route)
         if flavor == "traditional" then