Since 2.2.6 ssh credentials on git push seems to have a problem.
When i revert back to 2.2.5 everything works as expected.
I'm using jenkins credential with a ssh key.
Don't know if that has something to say, but I'm using env var's to set the git url, and in the failing log it's not resolved. But I guess the error prints it before the resolution, because the connection itself seems to work, just not the authentication.
I attached a log success.txt (with version 2.2.5) and a failing.txt (version 2.2.6). The only difference is that i reverted the plugin to 2.2.5 and everything worked again.
let me know if you need more information. But maybe so find the problem due the recent changes.