When trying to connect to a IBM Z/OS machine, tramp fails at the first test saying

tramp-file-name-handler: ‘echo \"‘uname -sr‘\"’ does not return a valid Lisp expression: ‘OS/390 26.00

’

After wandering through the source code for couple of days, I can't figure out what's wrong. Well, I only know beginner level lisp for one thing. The lack of comments anywhere doesn't help either.

Actually running echo \"‘uname -sr‘\" returns "OS/390 26.00" on my Z/OS machine.

Thanks, please someone help me out. I have spend 4 hours on this, as of now without any results.