fix: rename keepalive_supported back to keepalive to maintain compatability (even though its internal)

Author: GuyLewin

Diff for: lib/resty/http.lua

@@ -135,7 +135,7 @@ function _M.new(_)
         return nil, err
     end
     return setmetatable({
-        sock = sock, keepalive_supported = true, keepalive_ready = false, pool_only_after_response = false
+        sock = sock, keepalive = true, keepalive_ready = false, pool_only_after_response = false
     }, mt)
 end
 
@@ -197,7 +197,7 @@ function _M.tcp_only_connect(self, ...)
         self.port = nil
     end
 
-    self.keepalive_supported = true
+    self.keepalive = true
     self.ssl = false
 
     return sock:connect(...)
@@ -210,7 +210,7 @@ function _M.set_keepalive(self, ...)
         return nil, "not initialized"
     end
 
-    if self.keepalive_supported == true then
+    if self.keepalive == true then
         if self.pool_only_after_response and not self.keepalive_ready then
             return nil, "response not fully read"
         end
@@ -814,12 +814,12 @@ function _M.read_response(self, params)
     if ok then
         if (version == 1.1 and str_find(connection, "close", 1, true)) or
            (version == 1.0 and not str_find(connection, "keep-alive", 1, true)) then
-            self.keepalive_supported = false
+            self.keepalive = false
         end
     else
         -- no connection header
         if version == 1.0 then
-            self.keepalive_supported = false
+            self.keepalive = false
         end
     end