SFTP session fails to close

I'm trying to upgrade from ssh2 0.8.7 to git master (1.7.0 failed to build due to #1149 or something similar), and I'm having troubles with my sftp server not closing the connection correctly. If I'm using the standard tool sftp -vvv to retreive a file, this is where it stops:

debug3: Sent message SSH2_FXP_CLOSE I:8
debug3: SSH2_FXP_STATUS 0
debug2: channel 0: read<=0 rfd 4 len 0
debug2: channel 0: read failed
debug2: channel 0: close_read
debug2: channel 0: input open -> drain
debug2: channel 0: ibuf empty
debug2: channel 0: send eof
debug3: send packet: type 96
debug2: channel 0: input drain -> closed

After some research, I found RFC 4254 which claims that type 96 is SSH_MSG_CHANNEL_EOF and that Upon receiving this message, a party MUST send back an SSH_MSG_CHANNEL_CLOSE.

It looks to me like the sftp server does not do this correctly (i e, send back a SSH_MSG_CHANNEL_CLOSE), and so the connection stalls.

Start by reproducing the stall with the standard sftp -vvv tool and compare the exchange with RFC 4254, especially the SSH_MSG_CHANNEL_EOF and SSH_MSG_CHANNEL_CLOSE messages. Done means determining whether the ssh2 server-side behavior or the SFTP server is responsible and documenting a concrete path to prevent the connection from stalling.