dirstate: fix restoration of "merged" state after a remove Before this change, "merged" file that get removed and re-added later were recorded as "from_p2" instead. This came from 8fe74328f700, a 2014 changeset that start explicitly doing so for reason I have not been able to fully grasp. The graft test mentioned in the description are still happy after this changeset. So this changeset restore what seems to be the intended behavior. Restoring information as it was before the removal. Differential Revision: https://phab.mercurial-scm.org/D11429