From https://confluence.atlassian.com/bamkb/unable-to-detect-latest-git-changes-ssh-variant-simple-does-not-support-setting-port-943532118.html, it seems like git 2.16 doesn’t work with SSH executable bundled with IntelliJ 2017.3.
Git version 2.16.0-rc0 does not work well with OpenSSH version 6.7 or older as stated in this bug report.
Changing IntelliJ configuration to use “SSH Executable -> Native” fixed this issue.
