bug#40156: 26.3; append-to-file does not work on nonexistent file over ssh

[Sean Devlin]

Hi folks,

I did a little digging, and I think the problem is in 
tramp-sh-handle-write-region around line 3240:

>         ;; If `append' is non-nil, we copy the file locally, and let
>         ;; the native `write-region' implementation do the job.
>         (when append (copy-file filename tmpfile 'ok))



It looks like copy-file fails if filename doesn’t exist. Adding a test for file 
existence (i.e. file-exists-p) to the condition seems to solve the problem, 
though admittedly I only tested for my own narrow use case.

Thanks!