SSH hangs after upgrade to 1.6

[tastytea]

• Gitea version (or commit ref): 1.6.0
• Git version: 2.18.1
• Operating system: Gentoo Linux
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
  • Not relevant
• Log gist:

Description

I'm using the builtin SSH server. After I've upgraded Gitea from 1.5.3 to 1.6.0, I can no longer perform any operation over SSH. This is what shows up in the logfile:

2018/11/23 10:00:08 [T] SSH: Handshaking for [xxxx:c0:871f:3700:95f1:274b:1e07:7d0e]:52886
2018/11/23 10:00:08 [T] SSH: Connection from [xxxx:c0:871f:3700:95f1:274b:1e07:7d0e]:52886 (SSH-2.0-OpenSSH_7.7)
2018/11/23 10:00:08 [W] SSH: Invalid env arguments: '[]string{"\x04LANG"}'
2018/11/23 10:00:08 [W] SSH: Invalid env arguments: '[]string{"\tCOLORTERM"}'
2018/11/23 10:00:08 [W] SSH: Invalid env arguments: '[]string{"\bLC_CTYPE"}'
2018/11/23 10:00:08 [W] SSH: Invalid env arguments: '[]string{"\aLC_TIME"}'
2018/11/23 10:00:08 [T] SSH: Payload: git-receive-pack 'tastytea/overlay.git'
2018/11/23 10:00:08 [T] SSH: Arguments: [serv key-1 --config=/var/lib/gitea/conf/app.ini]

This is the output of GIT_SSH_COMMAND="ssh -vvv" git push all:
ssh.log

I could push to the same repository right before the upgrade. If I downgrade Gitea to 1.5.3, the problem persists. I've tried to clone multiple repositories, it never succeeds. Cloning over HTTPS works.

[tastytea]

Oops, nevermind. I forgot that I changed ENABLED to true under [markup.asciidoc]. After I copied the RENDER_COMMAND line from app.ini.example to app.ini, everything works again. 🤦