view tests/test-merge8.t @ 20275:2123d27ff75d

backout: avoid update on simple case.

Before the changeset the backout process was:
1) go to <target>
2) revert to <target> parent
3) update back to changeset we came from

The two update steps can takes a very long time to move back and forth unrelated
file change between <target> and current working directory.

The new process is just merging current working directory with the parent of
<target> using <target> as ancestor. This give the very same result but skip
the two updates. On big repo with a lot of files and changes that save a lots of
time (x20 for one week window).

The "merge" version (hg backout --merge) is still done with upgrades. We could
imagine using in memory commit to speed it up but this is another fish.

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 ..