[Bitbucket] Fixed error_msg concatenation error in raise_for_status

Author: Viktxrrr

atlassian/bitbucket/cloud/base.py

@@ -113,7 +113,7 @@ def raise_for_status(self, response):
                 e = j["error"]
                 error_msg = e["message"]
                 if e.get("detail"):
-                    error_msg += "\n" + e["detail"]
+                    error_msg = f"{error_msg}\n{e['detail']}"
             except Exception as e:
                 log.error(e)
                 response.raise_for_status()