emacs -Q
C-x C-f /:/tmp/foobar.txt (it doesn't matter whether the file exists)
M-: (process-file "true")
will result in an error
Debugger entered--Lisp error: (file-missing "Setting current directory" "No such file or directory" "/:/tmp/")
call-process("true" nil nil nil)
apply(call-process "true" nil nil nil nil)
process-file("true" nil nil nil)
apply(process-file ("true" nil nil nil))
file-name-non-special(process-file "true" nil nil nil)
apply(file-name-non-special process-file "true" nil nil nil nil)
process-file("true" nil nil nil)
apply(process-file ("true" nil nil nil))
tramp-run-real-handler(process-file ("true" nil nil nil))
tramp-file-name-handler(process-file "true" nil nil nil)
apply(tramp-file-name-handler process-file "true" nil nil nil nil)
process-file("true")
eval((process-file "true") nil)
eval-_expression_((process-file "true") nil)
funcall-interactively(eval-_expression_ (process-file "true") nil)
call-interactively(eval-_expression_ nil nil)
command-execute(eval-_expression_)
Attached a patch.