Prevent adding of extra space to value if property already exists

* org.el (org-entry-put): Prevent adding of extra space to value if
  property already exists.

Fixes a regression reported by Wujun Zhou.

lisp/org.el

@@ -13900,13 +13900,13 @@ and the new value.")
 	  (if (re-search-forward
 	       (org-re-property property) (cdr range) t)
 	      (progn
-		(delete-region (match-beginning 1) (match-end 1))
-		(goto-char (match-beginning 1)))
+		(delete-region (match-beginning 0) (match-end 0))
+		(goto-char (match-beginning 0)))
 	    (goto-char (cdr range))
 	    (insert "\n")
 	    (backward-char 1)
-	    (org-indent-line-function)
-	    (insert ":" property ":"))
+	    (org-indent-line-function))
+	  (insert ":" property ":")
 	  (and value (insert " " value))
 	  (org-indent-line-function)))))
     (run-hook-with-args 'org-property-changed-functions property value)))