https://github.com/redis/redis-py/issues/3057

--- /dev/null
+++ redis-5.0.7/dockers/stunnel/keys/server-cert.pem
@@ -0,0 +1,21 @@
+-----BEGIN CERTIFICATE-----
+MIIDYDCCAkgCAQEwDQYJKoZIhvcNAQEFBQAwdTELMAkGA1UEBhMCQ0ExETAPBgNV
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+T2gHdQ==
+-----END CERTIFICATE-----