[automerger skipped] Merge "init: add umount_all builtin." am: e438843ead
am: b2032ff720 -s ours
am skip reason: change_id Id3ab65b3860b6ea6cfec310ab13652009c81f415 with SHA1 81f1385589 is in history

Change-Id: I92f678cc6d11dd526f8c5c17f65cf0033b487ced