From a8046ffe2d47b044b0e043de8623adbc2f5ba560 Mon Sep 17 00:00:00 2001
From: Ed Catmur <edward.catmur@mavensecurities.com>
Date: Tue, 28 Jun 2022 15:50:28 +0100
Subject: [PATCH] don't set nested exception if already set

---
 include/pybind11/pytypes.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/pytypes.h b/include/pybind11/pytypes.h
index f5ba91206..9205e2b38 100644
--- a/include/pybind11/pytypes.h
+++ b/include/pybind11/pytypes.h
@@ -581,7 +581,8 @@ public:
     error_already_set()
         : m_fetched_error{new detail::error_fetch_and_normalize("pybind11::error_already_set"),
                           m_fetched_error_deleter} {
-        static_cast<std::nested_exception&>(*this) = m_fetched_error->get_cause_as_nested();
+        if (not nested_ptr())
+            static_cast<std::nested_exception&>(*this) = m_fetched_error->get_cause_as_nested();
     }
 
     /// The what() result is built lazily on demand.