The code in question
Net::SSH.start('server name', 'user')
This returns "non-absolute home". The 'user' in fact does have a home directory. One suggested approach was to modify ~/.ssh/config with full paths to the IdentityFile. This did not solve the issue.
The crazy part of this is that the code works fine if called through irb or console. The moment we try calling it from within a class method (with the same code) it returns the "non-absolute home" error.
The 'user' can also ssh into the server via command line without issue. The server is running Ubuntu.
UPDATE
Thanks to @Phrogz - The fix for this was setting ENV['HOME'] to '/home/deploy'. However, I have not figured out why $HOME is getting set to "." on the server. So, I will leave this question up without an "Answer" until I, or someone else, figures that out. Having to manually set HOME feels more like a "hack" than a proper solution, but it does work.