Esse é o comportamento padrão do SVN ao trabalhar com um certificado em que ele não confia. Dê uma olhada na seção SSL Certificate Management em " Controle de Versão com Subversion ".
If the client receives a server certificate, it needs to verify that it trusts the certificate: is the server really who it claims to be? The OpenSSL library does this by examining the signer of the server certificate, or certifying authority (CA). If OpenSSL is unable to automatically trust the CA, or if some other problem occurs (such as an expired certificate or hostname mismatch), the Subversion command-line client will ask you whether you want to trust the server certificate anyway.
This dialogue should look familiar; it's essentially the same question you've probably seen coming from your web browser (which is just another HTTP client like Subversion). If you choose the (p)ermanent option, the server certificate will be cached in your private run-time auth/ area in just the same way your username and password are cached (see the section called “Client Credentials Caching”). If cached, Subversion will automatically trust this certificate in future negotiations.
Parece que a solução é apenas executá-lo manualmente e aceitar o certificado permanentemente ou definir ssl-trust-default-ca
como true em sua configuração.
Many OpenSSL installations also have a pre-defined set of “default” CAs that are nearly universally trusted. To make the Subversion client automatically trust these standard authorities, set the ssl-trust-default-ca variable to true.