Hi all,

When trying to render a dot file with utf-8 encoded  characters,
org babel complained about the encodings. I cross checked ob-go.el at
line 107-108 and made an identical patch to make utf-8 dot files work:

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
diff --git "a/elpa\\org-9.1.14\\ob-dot.el"
"b/\\emacs261\\share\\emacs\\26.1\\lisp\\org\\ob-dot.el"
index 0fe50d4..31e0a4f 100644
--- "a/elpa\\org-9.1.14\\ob-dot.el"
+++ "b/\\emacs261\\share\\emacs\\26.1\\lisp\\org\\ob-dot.el"
@@ -69,8 +69,6 @@ This function is called by `org-babel-execute-src-block'."
         (cmdline (or (cdr (assq :cmdline params))
                      (format "-T%s" (file-name-extension out-file))))
         (cmd (or (cdr (assq :cmd params)) "dot"))
-     (coding-system-for-read 'utf-8) ;; use utf-8 with subprocesses
-     (coding-system-for-write 'utf-8)
         (in-file (org-babel-temp-file "dot-")))
     (with-temp-file in-file
       (insert (org-babel-expand-body:dot body params)))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

It took me some time. Hope to see it in next version if you think it's OK.

Best Regards,

Sig Tzeng

Emacs  : GNU Emacs 26.1 (build 1, x86_64-w64-mingw32)
 of 2018-05-30
Package: Org mode version 9.1.14 (9.1.14-1-g4931fc-elpa @
c:/Users/sig/emacs261/.emacs.d/elpa/org-9.1.14/)