Removed problematic assert that caused compatibility issues

Fixes #123.

CHANGES.rst

@@ -3,6 +3,11 @@ Version history
 
 This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
 
+**UNRELEASED**
+
+- Removed an ``assert`` in ``exceptiongroup._formatting`` that caused compatibility
+  issues with Sentry (`#123 <https://github.com/agronholm/exceptiongroup/issues/123>`_)
+
 **1.2.1**
 
 - Updated the copying of ``__notes__`` to match CPython behavior (PR by CF Bolz-Tereick)

src/exceptiongroup/_formatting.py

@@ -391,8 +391,6 @@ def format_exception_only(self):
 
     import apport_python_hook
 
-    assert sys.excepthook is apport_python_hook.apport_excepthook
-
     # monkeypatch the sys module that apport has imported
     fake_sys = ModuleType("exceptiongroup_fake_sys")
     fake_sys.__dict__.update(sys.__dict__)