org-element: Fix cache bug

* lisp/org-element.el (org-element--cache-for-removal): Be more
  careful when altering a properties drawer.

* testing/lisp/test-org-element.el (test-org-element/cache): Add test.

lisp/org-element.el

@@ -5451,13 +5451,20 @@ changes."
       (let ((up before)
 	    (robust-flag t))
 	(while up
-	  (if (and (memq (org-element-type up)
-			 '(center-block drawer dynamic-block
-					quote-block special-block))
-		   (let ((cbeg (org-element-property :contents-begin up)))
-		     (and cbeg
-			  (<= cbeg beg)
-			  (> (org-element-property :contents-end up) end))))
+	  (if (let ((type (org-element-type up)))
+		(and (or (memq type '(center-block dynamic-block quote-block
+						   special-block))
+			 ;; Drawers named "PROPERTIES" are probably
+			 ;; a properties drawer being edited.  Force
+			 ;; parsing to check if editing is over.
+			 (and (eq type 'drawer)
+			      (not (string=
+				    (org-element-property :drawer-name up)
+				    "PROPERTIES"))))
+		     (let ((cbeg (org-element-property :contents-begin up)))
+		       (and cbeg
+			    (<= cbeg beg)
+			    (> (org-element-property :contents-end up) end)))))
 	      ;; UP is a robust greater element containing changes.
 	      ;; We only need to extend its ending boundaries.
 	      (org-element--cache-shift-positions

testing/lisp/test-org-element.el

@@ -3488,6 +3488,15 @@ Text
 	   (search-forward "# ")
 	   (delete-char -1)
 	   (search-backward "Para1")
+	   (org-element-type (org-element-at-point))))))
+  ;; Corner case: watch out drawers named "PROPERTIES" as they are
+  ;; fragile, unlike to other drawers.
+  (should
+   (eq 'node-property
+       (org-test-with-temp-text "* H\n:PROPERTIES:\n:A: 1\n:A<point>\n:END:"
+	 (let ((org-element-use-cache t))
+	   (org-element-at-point)
+	   (insert "+:")
 	   (org-element-type (org-element-at-point)))))))