@param transport a smart transport
@param cert the certificate to pass to the caller
@param valid whether we believe the certificate is valid
@param hostname the hostname we connected to
@return the return value of the callback: 0 for no error, git_error_code.GIT_PASSTHROUGH
to indicate that there is no callback registered (or the callback
refused to validate the certificate and callers should behave as
if no callback was set), or < 0 for an error
Call the certificate check for this transport.
@param transport a smart transport @param cert the certificate to pass to the caller @param valid whether we believe the certificate is valid @param hostname the hostname we connected to @return the return value of the callback: 0 for no error, git_error_code.GIT_PASSTHROUGH to indicate that there is no callback registered (or the callback refused to validate the certificate and callers should behave as if no callback was set), or < 0 for an error