tests/test-merge8.t

revert: group related data in tuple in the dispatch table

The dispatch table used to be:

- action if in target manifest
- action if not in target manifest
- make backup if in target manifest
- make backup if not in target manifest

We turn this into two (action, make backup) tuples.

This helps both readability of the dispatch table and handling of each case.

This also prepares a refactoring where the different actions we performs, whether
"file is in target manifest" or not, are determined before reaching this loop.

Test for changeset ba7c74081861
(update dirstate correctly for non-branchmerge updates)
  $ hg init a
  $ cd a
  $ echo a > a
  $ hg add a
  $ hg commit -m a
  $ cd ..
  $ hg clone a b
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd a
  $ hg mv a b
  $ hg commit -m move
  $ echo b >> b
  $ hg commit -m b
  $ cd ../b
  $ hg pull ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  (run 'hg update' to get a working copy)
  $ hg update
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cd ..