1>i applied patch to patch(changeset-10) and commited it
  and gave it for review
2>i was told to make changes but now there
  has been a lot of changes
  so i did hg pull --rebase
  bookmark it as tip
3>Now i have two bookmarks
  a)tip (current changeset)  b)patch (changeset-10)
4>As i submit patch to phabricator using moz-phab
  it requires only the changeset on which i wrote the patch
  i.e (changeset-10)
5>Now what i want is not loose this (patch bookmark) changeset
  and at same time commit to newest pulled repo so that i
  am up to date ,as if i changed the changeset of "patch"
  to of "tip" it'll create a new changeset which i don't want