Bug: R src blocks fail to produce link to graphics file [9.3 org-plus-contrib-20200127]

[Tyler Smith]

To reproduce:

1. Start from `emacs -Q`

2. open the following org file:

```
#+BEGIN_SRC elisp setup
(require 'package)
(setq package-load-list
      '((org-plus-contrib t)
        (ess t)
        (julia-mode t)))
(package-initialize)
(require 'org)
(require 'ess)

(org-babel-do-load-languages
 'org-babel-load-languages
 '((emacs-lisp . t)
   (R . t)
   (shell . t)))
#+END_SRC

#+RESULTS:

#+begin_src R :results graphics :file test.jpg
plot (1:10)
#+end_src
```

3. Evaluate the first code block (C-c C-c) to load ess and setup babel to 
evaluate R code blocks

4.  Evaluate the second code block.

What I expect: 

A `#+RESULTS:` block is inserted, with a link to the file test.jpg;

What happens instead:

A message appears in the minibuffer:   'Code block produced no output'.

This worked previously. I'm not sure when it broke - sometime in the last two 
months I think, as I demoed this feature for colleagues in November.

Emacs state provided below.

Best,

Tyler

Emacs  : GNU Emacs 28.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
 of 2020-01-02
Package: Org mode version 9.3 (release_9.3 @ 
/home/smithty/.emacs.d/elpa/org-plus-contrib-20200127/)

current state:
==============
(setq
 org-src-mode-hook '(org-src-babel-configure-edit-buffer 
org-src-mode-configure-edit-buffer)
 org-link-shell-confirm-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 org-mode-hook '(org-eldoc-load
                 #[0 "\300\301\302\303\304$\207"
                   [add-hook change-major-mode-hook org-show-all append local] 
5]
                 #[0 "\300\301\302\303\304$\207"
                   [add-hook change-major-mode-hook org-babel-show-result-all 
append local] 5]
                 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-archive-hook '(org-attach-archive-delete-maybe)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-bibtex-headline-format-function #[257 "\300
\236A\207" [:title] 3 "\n\n(fn 
ENTRY)"]
 org-babel-pre-tangle-hook '(save-buffer)
 org-tab-first-hook '(org-babel-hide-result-toggle-maybe 
org-babel-header-arg-expand)
 org-babel-load-languages '((emacs-lisp . t) (R . t) (shell . t))
 org-src-lang-modes '(("redis" . redis) ("php" . php) ("arduino" . arduino) 
("C" . c) ("C++" . c++)
                      ("asymptote" . asy) ("bash" . sh) ("beamer" . latex) 
("calc" . fundamental)
                      ("cpp" . c++) ("ditaa" . artist) ("dot" . fundamental) 
("elisp" . emacs-lisp)
                      ("ocaml" . tuareg) ("screen" . shell-script) ("shell" . 
sh) ("sqlite" . sql))
 org-occur-hook '(org-first-headline-recenter)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-show-empty-lines
                  org-optimize-window-after-visibility-change)
 org-speed-command-hook '(org-speed-command-activate 
org-babel-speed-command-activate)
 org-confirm-shell-link-function 'yes-or-no-p
 org-link-parameters '(("attachment" :follow org-attach-open-link :export 
org-attach-export-link
                        :complete org-attach-complete-link)
                       ("id" :follow org-id-open) ("eww" :follow eww :store 
org-eww-store-link)
                       ("rmail" :follow org-rmail-open :store 
org-rmail-store-link)
                       ("mhe" :follow org-mhe-open :store org-mhe-store-link)
                       ("irc" :follow org-irc-visit :store org-irc-store-link 
:export org-irc-export)
                       ("info" :follow org-info-open :export org-info-export 
:store
                        org-info-store-link)
                       ("gnus" :follow org-gnus-open :store org-gnus-store-link)
                       ("docview" :follow org-docview-open :export 
org-docview-export :store
                        org-docview-store-link)
                       ("bibtex" :follow org-bibtex-open :store 
org-bibtex-store-link)
                       ("bbdb" :follow org-bbdb-open :export org-bbdb-export 
:complete
                        org-bbdb-complete-link :store org-bbdb-store-link)
                       ("w3m" :store org-w3m-store-link) ("file+sys") 
("file+emacs")
                       ("shell" :follow org-link--open-shell)
                       ("news" :follow
                        #[257 "\301\300\302Q!\207" ["news" browse-url ":"] 5 
"\n\n(fn URL)"])
                       ("mailto" :follow
                        #[257 "\301\300\302Q!\207" ["mailto" browse-url ":"] 5 
"\n\n(fn URL)"])
                       ("https" :follow
                        #[257 "\301\300\302Q!\207" ["https" browse-url ":"] 5 
"\n\n(fn URL)"])
                       ("http" :follow
                        #[257 "\301\300\302Q!\207" ["http" browse-url ":"] 5 
"\n\n(fn URL)"])
                       ("ftp" :follow
                        #[257 "\301\300\302Q!\207" ["ftp" browse-url ":"] 5 
"\n\n(fn URL)"])
                       ("help" :follow org-link--open-help)
                       ("file" :complete org-link-complete-file)
                       ("elisp" :follow org-link--open-elisp) ("doi" :follow 
org-link--open-doi))
 org-link-elisp-confirm-function 'yes-or-no-p
 )


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