rebar3/ssh fetch failure

[essen]

Trying to fetch from git+ssh from a new host that wasn't yet added to the list of allowed hosts:

===> Verifying dependencies...
===> Fetching cowboy ({git,"[email protected]",
                                  {tag,"secret-tag"}})
===> Failed to fetch and copy dep: {git,"[email protected]",
                                   {tag,"secret-tag"}}

Trying manually:

% git clone [email protected]
Cloning into 'cowboy'...
The authenticity of host 'secret-server (secret-ip-address)' can't be established.
ECDSA key fingerprint is SHA256:secret-fingerprint.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'secret-server' (ECDSA) to the list of known hosts.

I'd expect rebar3 to give me the yes/no prompt, or at least a more helpful message by default.