Adding Certificate to ca-bundle.crt has no effect

[ip6li]

Steps to reproduce:

• install collabora office
• run docker container
• get certificate with echo | openssl s_client -connect localhost:9980
• add certificate data returned from command above to resources/config/ca-bundle.crt

After click to office following message appears:

Collabora Online: SSL-Zertifikat ist nicht installiert.

Bitten Sie Ihren Administrator die ca-chain.cert.pem zum ownCloud ca-bundle.crt hinzuzufügen. Z.B. "cat /etc/loolwsd/ca-chain.cert.pem >> /resources/config/ca-bundle.crt". Die genaue Fehlermeldung war:cURL error 60: SSL certificate problem: self signed certificate in certificate chain

Expected behaviour: Certificate should be accepted.