org-element: Fix test failure

* lisp/org-element.el (org-element--current-element): Fix regexp.

lisp/org-element.el

@@ -3890,7 +3890,7 @@ element it has to parse."
 	      (goto-char (car affiliated))
 	      (org-element-keyword-parser limit nil))
 	     ;; LaTeX Environment.
-	     ((looking-at "[ \t]*\\\\begin{\\([A-Za-z0-9]+\\*?\\)}")
+	     ((looking-at "[ \t]*\\\\begin{\\([A-Za-z0-9]+\\*?\\)}\\(\\[.*?\\]\\|{.*?}\\)*[ \t]*$")
 	      (org-element-latex-environment-parser limit affiliated))
 	     ;; Drawer and Property Drawer.
 	     ((looking-at org-drawer-regexp)