Add a second `collect()` call which hopefully will make the test pass on PyPy.
diff --git a/OpenSSL/test/test_ssl.py b/OpenSSL/test/test_ssl.py
index 228d9c5..ea4fceb 100644
--- a/OpenSSL/test/test_ssl.py
+++ b/OpenSSL/test/test_ssl.py
@@ -1158,6 +1158,12 @@
del callback
context.set_tlsext_servername_callback(replacement)
+
+ # One run of the garbage collector happens to work on CPython. PyPy
+ # doesn't collect the underlying object until a second run for whatever
+ # reason. That's fine, it still demonstrates our code has properly
+ # dropped the reference.
+ collect()
collect()
callback = tracker()