properly merge pypy coverage with coveragerc paths
diff --git a/.coveragerc b/.coveragerc
index a0a57b3..62a0ff5 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -8,6 +8,7 @@
 source =
    src/cryptography
    .tox/*/lib/python*/site-packages/cryptography
+   .tox/pypy/site-packages/cryptography
 
 [report]
 exclude_lines =