bug#39994: 27.0.90; Broken image-converter probe for imagemagick

[Juri Linkov <juri@linkov.net>]

Tags: patch

I tried to visit an .ico file using graphicsmagick image-converter,
but it failed with the error:

  Cannot display image: (/usr/bin/gm convert: Unexpected end-of-file ().

Probably a bug in graphicsmagick, so we can do nothing to fix this.

Then I tried imagemagick, but image-converter said .ico format is unsupported.
Whereas running `convert -list format` outputs:

   Format  Module    Mode  Description
-------------------------------------------------------------------------------
      ICO* ICON      rw+   Microsoft icon

So this patch adds the support for the 'Module' column to imagemagick probe:

diff --git a/lisp/image/image-converter.el b/lisp/image/image-converter.el
index 0488a13d41..5843b2a399 100644
--- a/lisp/image/image-converter.el
+++ b/lisp/image/image-converter.el
@@ -44,8 +44,8 @@ image-converter-regexp
 
 (defvar image-converter--converters
   '((graphicsmagick :command ("gm" "convert") :probe ("-list" "format"))
-    (ffmpeg :command "ffmpeg" :probe "-decoders")
-    (imagemagick :command "convert" :probe ("-list" "format")))
+    (imagemagick :command "convert" :probe ("-list" "format"))
+    (ffmpeg :command "ffmpeg" :probe "-decoders"))
   "List of supported image converters to try.")
 
 (defun image-convert-p (source &optional data-p)
@@ -150,7 +150,7 @@ image-converter--probe
         (forward-line 1)
         ;; Lines look like
         ;; "      WPG* r--   Word Perfect Graphics".
-        (while (re-search-forward "^ *\\([A-Z0-9]+\\)\\*? +r" nil t)
+        (while (re-search-forward "^ *\\([A-Z0-9]+\\)\\*?\\(?: +[A-Z0-9]+\\)? +r" nil t)
           (push (downcase (match-string 1)) formats)))
       (nreverse formats))))