stubby: TLS verification fails on self-signed certificates with LibreSSL 2.7, pass with OpenSSL

Hello, Stubby is able to run in strict mode with LibreSSL since 2.7 release. This version supports now OpenSSL 1.0.2 and 1.1 APIs. It works with servers that have a certificate signed by an authority. However, TLS verification fails on self-signed certificates. Here is a debug log with Lorraine Data Network server which have a self-signed certificate:

[12:04:55.862914] STUBBY: 80.67.188.188                            : Conn opened: TLS - Strict Profile
[12:04:55.918753] STUBBY: 80.67.188.188                            : Verify failed: TLS - *Failure* -  (18) "self signed certificate"
[12:04:55.918834] STUBBY: 80.67.188.188                            : Conn closed: TLS - *Failure*
[12:04:55.918845] STUBBY:    *FAILURE* no valid transports or upstreams available!
[12:04:55.918918] STUBBY: 80.67.188.188                            : Conn closed: TLS - Resps=     0, Timeouts  =     0, Curr_auth = Failed, Keepalive(ms)=     0
[12:04:55.918930] STUBBY: 80.67.188.188                            : Upstream   : TLS - Resps=     0, Timeouts  =     0, Best_auth = Failed
[12:04:55.918936] STUBBY: 80.67.188.188                            : Upstream   : TLS - Conns=     0, Conn_fails=     1, Conn_shuts=      0, Backoffs     =     0