From aa76f9b569ea1153e7bececf40870f224c9990a5 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Thu, 8 Sep 2022 20:44:11 +0200
Subject: [PATCH] Backport PR #48416: REF: ensure to apply suffixes before
 concat step in merge code

---
 pandas/core/reshape/merge.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/reshape/merge.py b/pandas/core/reshape/merge.py
index 159ab33a8a04f..fe51230961327 100644
--- a/pandas/core/reshape/merge.py
+++ b/pandas/core/reshape/merge.py
@@ -764,8 +764,9 @@ def _reindex_and_concat(
 
         from pandas import concat
 
+        left.columns = llabels
+        right.columns = rlabels
         result = concat([left, right], axis=1, copy=copy)
-        result.columns = llabels.append(rlabels)
         return result
 
     def get_result(self, copy: bool = True) -> DataFrame: