FIX: deleting a flagged post issue

cf. http://meta.discourse.org/t/deleting-a-flagged-post-issue/10061

The bug was only happening when you were about the delete the first post, which means deleting the entire topic.

test/javascripts/admin/models/flagged_post_test.js

@@ -0,0 +1,19 @@
+module("Discourse.FlaggedPost");
+
+test('delete first post', function() {
+  this.stub(Discourse, 'ajax');
+
+  Discourse.FlaggedPost.create({ id: 1, topic_id: 2, post_number: 1 })
+           .deletePost();
+
+  ok(Discourse.ajax.calledWith("/t/2", { type: 'DELETE', cache: false }), "it deleted the topic");
+});
+
+test('delete second post', function() {
+  this.stub(Discourse, 'ajax');
+
+  Discourse.FlaggedPost.create({ id: 1, topic_id: 2, post_number: 2 })
+           .deletePost();
+
+  ok(Discourse.ajax.calledWith("/posts/1", { type: 'DELETE', cache: false }), "it deleted the post");
+});