SCP assert with the libssh backend

[bagder]

I did this

$ ./src/curl scp://localhost/ -u user:pwd
curl: ssh-libssh.c:1835: myssh_statemach_act: Assertion `sshc->scp_session == ((void *)0)' failed.
Aborted

I expected the following

Some sort of (nicer) run-time message about a failed transfer (since that's a directory and not a file). curl with the libssh2 backend says:

$ ./src/curl scp://localhost/ -u user:pwd
curl: (78) Failed to recv file

curl/libcurl version

git master as of July 5th 2018

curl 7.61.0-DEV (x86_64-pc-linux-gnu) libcurl/7.61.0-DEV (GnuTLS/3.5.18) OpenSSL/1.1.0h zlib/1.2.11 brotli/1.0.5 c-ares/1.14.0 libidn2/2.0.4 libpsl/0.20.2 (+libidn2/2.0.4) libssh/0.7.0/openssl/zlib nghttp2/1.33.0-DEV librtmp/2.3
Release-Date: [unreleased]
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtmp rtsp scp sftp smb smbs smtp smtps telnet tftp 
Features: AsynchDNS Debug TrackMemory IDN IPv6 Largefile GSS-API Kerberos SPNEGO NTLM NTLM_WB SSL libz brotli TLS-SRP HTTP2 UnixSockets HTTPS-proxy MultiSSL PSL Metalink 

operating system

Debian Linux

Related?

Possibly this, or a related issue was brought up on the mailing list by Martin Galvan

/cc @nmav