org.el: Don't exclude local tags that are also inherited

This fixes a bug in set-tags-command excluding a tag that is both set
locally and inherited from the initial minibuffer input by modifying
org-get-tags to prefer keeping the locally set tag over the inherited
tag, as this behavior is more intuitive for org-get-tags anyway.

* lisp/org.el (org-get-tags): Keep local tags over inherited.
* testing/lisp/test-org.el (test-org/set-tags-command): Add test.

lisp/org.el

@@ -12745,7 +12745,8 @@ According to `org-use-tag-inheritance', tags may be inherited
 from parent headlines, and from the whole document, through
 `org-file-tags'.  In this case, the returned list of tags
 contains tags in this order: file tags, tags inherited from
-parent headlines, local tags.
+parent headlines, local tags.  If a tag appears multiple times,
+only the most local tag is returned.
 
 However, when optional argument LOCAL is non-nil, only return
 tags specified at the headline.
@@ -12761,12 +12762,13 @@ Inherited tags have the `inherited' text property."
         (let ((ltags (org--get-local-tags)) itags)
           (if (or local (not org-use-tag-inheritance)) ltags
             (while (org-up-heading-safe)
-              (setq itags (append (mapcar #'org-add-prop-inherited
-                                          (org--get-local-tags))
-                                  itags)))
+              (setq itags (nconc (mapcar #'org-add-prop-inherited
+					 (org--get-local-tags))
+				 itags)))
             (setq itags (append org-file-tags itags))
-            (delete-dups
-             (append (org-remove-uninherited-tags itags) ltags))))))))
+            (nreverse
+	     (delete-dups
+	      (nreverse (nconc (org-remove-uninherited-tags itags) ltags))))))))))
 
 (defun org-get-buffer-tags ()
   "Get a table of all tags used in the buffer, for completion."

testing/lisp/test-org.el

@@ -6272,6 +6272,17 @@ Paragraph<point>"
 	      (let ((org-use-fast-tag-selection nil)
 		    (org-tags-column 1))
 		(org-set-tags-command)))
+	    (buffer-substring (point) (line-end-position)))))
+  ;; Handle tags both set locally and inherited.
+  (should
+   (equal "b :foo:"
+	  (org-test-with-temp-text "* a :foo:\n** <point>b :foo:"
+	    (cl-letf (((symbol-function 'completing-read)
+		       (lambda (prompt coll &optional pred req initial &rest args)
+			 initial)))
+	      (let ((org-use-fast-tag-selection nil)
+		    (org-tags-column 1))
+		(org-set-tags-command)))
 	    (buffer-substring (point) (line-end-position))))))
 
 (ert-deftest test-org/toggle-tag ()