ob-exp: Restore evaluation query for lob calls during export

* lisp/ob-exp.el (org-babel-exp-results): Fix a regression from v9.0
that led to silently executing lob calls on export despite a non-nil
value of org-confirm-babel-evaluate.
* testing/lisp/test-ob-lob.el (test-ob-lob/confirm-evaluate): New test.

56bf3d789 (Babel: avoid superfluous confirmation for internal wrapper,
2013-04-10) let-bound org-confirm-babel-evaluate to nil in two spots
to prevent double querying for lob calls.  These overrides were no
longer needed following the refactoring in dbb375fdf (Simplify Babel
calls evaluation, 2016-06-16).  However, that commit dropped only one
of the spots, and, as a result, disabled confirmation unconditionally
when exporting lob calls.

Drop the remaining org-confirm-babel-evaluate override.

Reported-by: 吴锐扬 <ywwry66@gmail.com>
Ref: https://orgmode.org/list/5362C0A0-632F-4C87-8FA1-915F0F53D8B8@gmail.com

lisp/ob-exp.el

@@ -405,8 +405,7 @@ inhibit insertion of results into the buffer."
 	  (`lob
 	   (save-excursion
 	     (goto-char (nth 5 info))
-	     (let (org-confirm-babel-evaluate)
-	       (org-babel-execute-src-block nil info)))))))))
+	     (org-babel-execute-src-block nil info))))))))
 
 (provide 'ob-exp)
 

testing/lisp/test-ob-lob.el

@@ -250,6 +250,34 @@ call_test-newline[:eval yes :results raw]('(1\n2))<point>"
 <point>#+call: bar()"
 	(org-babel-execute-src-block nil (org-babel-lob-get-info))))))
 
+(ert-deftest test-ob-lob/confirm-evaluate ()
+  "Test confirmation when exporting lob calls."
+  ;; With the default `org-confirm-babel-evaluate' of t, the caller is
+  ;; queried one time.
+  (should
+   (= 1
+      (let ((org-export-use-babel t)
+	    (org-confirm-babel-evaluate t)
+	    (confirm-evaluate-calls 0))
+	(cl-letf (((symbol-function 'yes-or-no-p)
+		   (lambda (&rest _ignore)
+		     (cl-incf confirm-evaluate-calls)
+		     t)))
+	  (org-test-with-temp-text
+	      "
+#+name: foo
+#+begin_src emacs-lisp
+  nil
+#+end_src
+
+#+call: foo()"
+	    (let ((string (buffer-string)))
+	      (with-temp-buffer
+		(org-mode)
+		(insert string)
+		(org-babel-exp-process-buffer)
+		confirm-evaluate-calls))))))))
+
 (provide 'test-ob-lob)
 
 ;;; test-ob-lob.el ends here