This comment claimed that set_dummy_rel_pathlist() has callers
other than (possibly indirectly) set_rel_size(). It doesn't,
so revise the argument to not rely on that.
Noted by Richard Guo.
Discussion: https://postgr.es/m/CAMbWs4-KFEU_fDuJPNCOkUu3rwvZvKBEytkd9VrM4kH4-2h1CQ@mail.gmail.com
/*
* We set the cheapest-path fields immediately, just in case they were
- * pointing at some discarded path. This is redundant when we're called
- * from set_rel_size(), but not when called from elsewhere, and doing it
- * twice is harmless anyway.
+ * pointing at some discarded path. This is redundant in current usage
+ * because set_rel_pathlist will do it later, but it's cheap so we keep it
+ * for safety and consistency with mark_dummy_rel.
*/
set_cheapest(rel);
}