diff --git a/mercurial/demandimport.py b/mercurial/demandimport.py
--- a/mercurial/demandimport.py
+++ b/mercurial/demandimport.py
@@ -255,6 +255,7 @@ ignore = [
     '_sre', # issue4920
     'rfc822',
     'mimetools',
+    'sqlalchemy.events', # has import-time side effects (issue5085)
     # setuptools 8 expects this module to explode early when not on windows
     'distutils.msvc9compiler'
     ]