Remove assertions in the set_tracefunc() method.

The assertions were actually incorrect if the same tracer object was set twice.

Removing the assertions is ok here because the reference handling is pretty thoroughly debugged and tested now.

3 files changed, 13 insertions, 5 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index 8a15aac..9f31503 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -5,7 +5,10 @@
 2.0.2 (unreleased)
 ==================
 
-- Nothing changed yet.
+- Fix calling ``greenlet.settrace()`` with the same tracer object that
+  was currently active. See `issue 332
+  <https://github.com/python-greenlet/greenlet/issues/332>`_.
+
 
 
 2.0.1 (2022-11-07)
diff --git a/src/greenlet/greenlet_thread_state.hpp b/src/greenlet/greenlet_thread_state.hpp
index 15111c5..b740874 100644
--- a/src/greenlet/greenlet_thread_state.hpp
+++ b/src/greenlet/greenlet_thread_state.hpp
@@ -307,11 +307,7 @@ public:
             this->tracefunc.CLEAR();
         }
         else {
-#ifndef NDEBUG
-            Py_ssize_t old_refs = Py_REFCNT(tracefunc);
-#endif
             this->tracefunc = tracefunc;
-            assert(this->tracefunc.REFCNT() == old_refs + 1);
         }
     }
 
diff --git a/src/greenlet/tests/test_tracing.py b/src/greenlet/tests/test_tracing.py
index 843e3cf..de84dbc 100644
--- a/src/greenlet/tests/test_tracing.py
+++ b/src/greenlet/tests/test_tracing.py
@@ -66,6 +66,15 @@ class TestGreenletTracing(TestCase):
             ('switch', (main, g)),
         ])
 
+    def test_set_same_tracer_twice(self):
+        # https://github.com/python-greenlet/greenlet/issues/332
+        # Our logic in asserting that the tracefunction should
+        # gain a reference was incorrect if the same tracefunction was set
+        # twice.
+        tracer = GreenletTracer()
+        with tracer:
+            greenlet.settrace(tracer)
+
 
 class PythonTracer(object):
     oldtrace = None