rebase: remove some redundant setting of dirstate parents Since we're now setting the dirstate parents to its correct values from the beginning (right after `merge.update()`), we usually don't need to set them again before committing. The only case we need to care about is when committing collapsed commits. So we can remove the `setparents()` calls just before committing and add one only for the collapse case. Differential Revision: https://phab.mercurial-scm.org/D7828