Removed an invalid assertion

src/account.cc

@@ -137,7 +137,10 @@ void account_t::add_post(post_t * post)
 
 bool account_t::remove_post(post_t * post)
 {
-  assert(! posts.empty());
+  // It's possible that 'post' wasn't yet in this account, but try to
+  // remove it anyway.  This can happen if there is an error during
+  // parsing, when the posting knows what it's account is, but
+  // xact_t::finalize has not yet added that posting to the account.
   posts.remove(post);
   post->account = NULL;
   return true;