fixed default header override caused by array union (#1727)

* Fix header merge

We should use array_merge to append and reindex header array, + causes an issue where if we add a header, like for example Authorization, then the first item in merged header will be skipped (Content-Type) as there will already be a header at 0 index of array. + does not replace values which keys already exist in arrays

* Update CHANGELOG.md

CHANGELOG.md

@@ -14,6 +14,7 @@
 ### Fixed
 - Fixed Range expansion when hosts.yml is loaded. [#1671]
 - Fixed usage (only if present) of deploy_path config setting. [#1677]
+- Fixed adding custom headers causes Httpie default header override.
 
 
 ## v6.3.0

src/Utility/Httpie.php

@@ -59,10 +59,10 @@ class Httpie
     {
         $http = clone $this;
         $http->body = json_encode($data, JSON_PRETTY_PRINT);
-        $http->headers += [
+        $http->headers = array_merge($http->headers, [
             'Content-Type: application/json',
             'Content-Length: ' . strlen($http->body)
-        ];
+        ]);
         return $http;
     }
 
@@ -70,10 +70,10 @@ class Httpie
     {
         $http = clone $this;
         $http->body = http_build_query($data);
-        $http->headers += [
+        $http->headers = array_merge($this->headers, [
             'Content-type: application/x-www-form-urlencoded',
             'Content-Length: ' . strlen($http->body)
-        ];
+        ]);
         return $http;
     }