Reverse the way backout is doing the merge
Currently, backout is creating a backout revision as a child node of the
backed out node and will leave you at this new head. This has several
drawbacks:
* this changes the current head
* when there is a long history between the backed out node and the
current head, this will generate a huge number of diffs that are scary
at first sight, and not very natural to review before commit.
The change consists to switch back to the original node as soon as the
backout node (which becomes the new tip) has been created. Then the
--merge option can just merge this new tip in the current node.
* the current head/node is not changed from the user's point of view
* even without using the --merge option, the backout revision is still
easy to locate, as this is the tip
* the merge is much more intuitive as diffs of the merge is right you
are looking to backout
# should complain
abort: please specify a revision to backout
abort: please specify just one revision
# basic operation
adding a
reverting a
changeset 2:2929462c3dff backs out changeset 1:a820f4f40a57
a
# file that was removed is recreated
adding a
adding a
changeset 2:de31bdc76c0d backs out changeset 1:76862dcce372
content
# backout of backout is as if nothing happened
removing a
changeset 3:7f6d0f120113 backs out changeset 2:de31bdc76c0d
cat: a: No such file or directory
# across branch
adding a
adding b
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
abort: cannot back out change on a different branch
adding c
abort: cannot back out change on a different branch
# backout with merge
adding a
reverting a
changeset 3:26b8ccb9ad91 backs out changeset 1:5a50a024c182
merging with changeset 3:26b8ccb9ad91
merging a
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
line 1
line 2
line 3
# backout should not back out subsequent changesets
adding a
adding b
reverting a
changeset 3:3202beb76721 backs out changeset 1:22bca4c721e5
the backout changeset is a new head - do not forget to merge
(use "backout --merge" if you want to auto-merge)
b
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
adding a
adding b
adding c
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
adding d
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
# backout of merge should fail
abort: cannot back out a merge changeset without --parent
# backout of merge with bad parent should fail
abort: cb9a9f314b8b is not a parent of b2f3bb92043e
# backout of non-merge with parent should fail
abort: cannot use --parent on non-merge changeset
# backout with valid parent should be ok
removing d
changeset 5:10e5328c8435 backs out changeset 4:b2f3bb92043e
rolling back last transaction
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
removing c
changeset 5:033590168430 backs out changeset 4:b2f3bb92043e