From 533f5718904b620be8d63f2474229945d6f8ba5d Mon Sep 17 00:00:00 2001
From: Federico Caselli <cfederico87@gmail.com>
Date: Thu, 9 Dec 2021 21:47:22 +0100
Subject: [PATCH] Include import error message when greenlet is not installed

Fixes: #7419
Change-Id: I0c604875a80287acff3bab732f67601a5e2db98c
---
 lib/sqlalchemy/util/concurrency.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/sqlalchemy/util/concurrency.py b/lib/sqlalchemy/util/concurrency.py
index 3518f874dc..2397c11897 100644
--- a/lib/sqlalchemy/util/concurrency.py
+++ b/lib/sqlalchemy/util/concurrency.py
@@ -7,10 +7,11 @@
 
 
 have_greenlet = False
-
+greenlet_error = None
 try:
     import greenlet  # noqa F401
-except ImportError:
+except ImportError as e:
+    greenlet_error = str(e)
     pass
 else:
     have_greenlet = True
@@ -37,6 +38,9 @@ if not have_greenlet:
 
         raise ValueError(
             "the greenlet library is required to use this function."
+            " %s" % greenlet_error
+            if greenlet_error
+            else ""
         )
 
     def is_exit_exception(e):  # noqa F811
-- 
2.47.3