emacs-29 7d6855c9ab6: Fix outgoing mime type regression (Bug#62815)

[Andrew G Cohen]

branch: emacs-29
commit 7d6855c9ab6e0d5128d81b4bcb685799a3c316e9
Author: Andrew G Cohen <cohen@andy.bu.edu>
Commit: Andrew G Cohen <cohen@andy.bu.edu>

    Fix outgoing mime type regression (Bug#62815)
    
    * lisp/net/mailcap.el (mailcap-mime-extensions,
    mailcap-parse-mimetype-file, mailcap-mime-types): Don't regexp-quote
    mimetypes in a context where they should be strings.
    (mailcap--regexp-quote-type): Remove.
    
    (cherry picked from commit 605414d018da47f99dec5019142f584b6eb174c8)
---
 lisp/net/mailcap.el | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/lisp/net/mailcap.el b/lisp/net/mailcap.el
index 722e98be2fc..be13272f3b0 100644
--- a/lisp/net/mailcap.el
+++ b/lisp/net/mailcap.el
@@ -979,7 +979,7 @@ If NO-DECODE is non-nil, don't decode STRING."
     (".vox"   . "audio/basic")
     (".vrml"  . "x-world/x-vrml")
     (".wav"   . "audio/x-wav")
-    (".xls"   . "application/vnd\\.ms-excel")
+    (".xls"   . "application/vnd.ms-excel")
     (".wrl"   . "x-world/x-vrml")
     (".xbm"   . "image/xbm")
     (".xpm"   . "image/xpm")
@@ -1051,8 +1051,7 @@ If FORCE, re-parse even if already parsed."
        (setq save-pos (point))
        (skip-chars-forward "^ \t\n")
        (downcase-region save-pos (point))
-       (setq type (mailcap--regexp-quote-type
-                    (buffer-substring save-pos (point))))
+       (setq type (buffer-substring save-pos (point)))
        (while (not (eolp))
          (skip-chars-forward " \t")
          (setq save-pos (point))
@@ -1065,12 +1064,6 @@ If FORCE, re-parse even if already parsed."
         (setq mailcap-mime-extensions (append extns mailcap-mime-extensions)
               extns nil)))))
 
-(defun mailcap--regexp-quote-type (type)
-  (if (not (string-search "/" type))
-      type
-    (pcase-let ((`(,major ,minor) (split-string type "/")))
-      (concat major "/" (regexp-quote minor)))))
-
 (defun mailcap-extension-to-mime (extn)
   "Return the MIME content type of the file extensions EXTN."
   (mailcap-parse-mimetypes)
@@ -1107,7 +1100,7 @@ For instance, `image/png' will result in `png'."
         (dolist (info (cdr data))
           (setq type (cdr (assq 'type (cdr info))))
           (unless (string-search "*" type)
-            (push type res))))
+            (push (string-replace "\\" "" type) res))))
       (nreverse res)))))
 
 ;;;