Criss cross merging

  $ hg init criss-cross

  $ cd criss-cross

  $ echo '0 base' > f1

  $ echo '0 base' > f2

  $ hg ci -Aqm '0 base'

  $ echo '1 first change' > f1

  $ hg ci -m '1 first change f1'

  $ hg up -qr0

  $ echo '2 first change' > f2

  $ hg ci -qm '2 first change f2'

  $ hg merge -qr 1

  $ hg ci -m '3 merge'

  $ hg up -qr2

  $ hg merge -qr1

  $ hg ci -qm '4 merge'

  $ echo '5 second change' > f1

  $ hg ci -m '5 second change f1'

  $ hg up -r3

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ echo '6 second change' > f2

  $ hg ci -m '6 second change f2'

  $ hg log -G

  @  changeset:   6:3b08d01b0ab5

  |  tag:         tip

  |  parent:      3:cf89f02107e5

  |  user:        test

  |  date:        Thu Jan 01 00:00:00 1970 +0000

  |  summary:     6 second change f2

  |

  | o  changeset:   5:adfe50279922

  | |  user:        test

  | |  date:        Thu Jan 01 00:00:00 1970 +0000

  | |  summary:     5 second change f1

  | |

  | o    changeset:   4:7d3e55501ae6

  | |\   parent:      2:40663881a6dd

  | | |  parent:      1:0f6b37dbe527

  | | |  user:        test

  | | |  date:        Thu Jan 01 00:00:00 1970 +0000

  | | |  summary:     4 merge

  | | |

  o---+  changeset:   3:cf89f02107e5

  | | |  parent:      2:40663881a6dd

  |/ /   parent:      1:0f6b37dbe527

  | |    user:        test

  | |    date:        Thu Jan 01 00:00:00 1970 +0000

  | |    summary:     3 merge

  | |

  | o  changeset:   2:40663881a6dd

  | |  parent:      0:40494bf2444c

  | |  user:        test

  | |  date:        Thu Jan 01 00:00:00 1970 +0000

  | |  summary:     2 first change f2

  | |

  o |  changeset:   1:0f6b37dbe527

  |/   user:        test

  |    date:        Thu Jan 01 00:00:00 1970 +0000

  |    summary:     1 first change f1

  |

  o  changeset:   0:40494bf2444c

     user:        test

     date:        Thu Jan 01 00:00:00 1970 +0000

     summary:     0 base

  $ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor='!'

  note: using 0f6b37dbe527 as ancestor of 3b08d01b0ab5 and adfe50279922

        alternatively, use --config merge.preferancestor=40663881a6dd

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922

   preserving f2 for resolve of f2

   f1: remote is newer -> g

  getting f1

   f2: versions differ -> m (premerge)

  picked tool ':dump' for f2 (binary False symlink False changedelete False)

  merging f2

  my f2@3b08d01b0ab5+ other f2@adfe50279922 ancestor f2@0f6b37dbe527

   f2: versions differ -> m (merge)

  picked tool ':dump' for f2 (binary False symlink False changedelete False)

  my f2@3b08d01b0ab5+ other f2@adfe50279922 ancestor f2@0f6b37dbe527

  1 files updated, 0 files merged, 0 files removed, 1 files unresolved

  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon

  [1]

  $ f --dump *

  f1:

  >>>

  5 second change

  <<<

  f2:

  >>>

  6 second change

  <<<

  f2.base:

  >>>

  0 base

  <<<

  f2.local:

  >>>

  6 second change

  <<<

  f2.orig:

  >>>

  6 second change

  <<<

  f2.other:

  >>>

  2 first change

  <<<

  $ hg up -qC .

  $ hg merge -v --tool internal:dump 5 --config merge.preferancestor="null 40663881 3b08d"

  note: using 40663881a6dd as ancestor of 3b08d01b0ab5 and adfe50279922

        alternatively, use --config merge.preferancestor=0f6b37dbe527

  resolving manifests

  merging f1

  0 files updated, 0 files merged, 0 files removed, 1 files unresolved

  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon

  [1]

Redo merge with merge.preferancestor="*" to enable bid merge

  $ rm f*

  $ hg up -qC .

  $ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor="*"

  note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd

  calculating bids for ancestor 0f6b37dbe527

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922

   f1: remote is newer -> g

   f2: versions differ -> m

  calculating bids for ancestor 40663881a6dd

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: 40663881a6dd, local: 3b08d01b0ab5+, remote: adfe50279922

   f1: versions differ -> m

   f2: remote unchanged -> k

  auction for merging merge bids (2 ancestors)

   list of bids for f1:

     remote is newer -> g

     versions differ -> m

   f1: picking 'get' action

   list of bids for f2:

     remote unchanged -> k

     versions differ -> m

   f2: picking 'keep' action

  end of auction

   f1: remote is newer -> g

  getting f1

   f2: remote unchanged -> k

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ f --dump *

  f1:

  >>>

  5 second change

  <<<

  f2:

  >>>

  6 second change

  <<<

The other way around:

  $ hg up -C -r5

  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg merge -v --debug --config merge.preferancestor="*"

  note: merging adfe50279922+ and 3b08d01b0ab5 using bids from ancestors 0f6b37dbe527 and 40663881a6dd

  calculating bids for ancestor 0f6b37dbe527

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: 0f6b37dbe527, local: adfe50279922+, remote: 3b08d01b0ab5

   f1: remote unchanged -> k

   f2: versions differ -> m

  calculating bids for ancestor 40663881a6dd

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: 40663881a6dd, local: adfe50279922+, remote: 3b08d01b0ab5

   f1: versions differ -> m

   f2: remote is newer -> g

  auction for merging merge bids (2 ancestors)

   list of bids for f1:

     remote unchanged -> k

     versions differ -> m

   f1: picking 'keep' action

   list of bids for f2:

     remote is newer -> g

     versions differ -> m

   f2: picking 'get' action

  end of auction

   f2: remote is newer -> g

  getting f2

   f1: remote unchanged -> k

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ f --dump *

  f1:

  >>>

  5 second change

  <<<

  f2:

  >>>

  6 second change

  <<<

Verify how the output looks and and how verbose it is:

  $ hg up -qC

  $ hg merge

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ hg up -qC tip

  $ hg merge -v

  note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd

  calculating bids for ancestor 0f6b37dbe527

  resolving manifests

  calculating bids for ancestor 40663881a6dd

  resolving manifests

  auction for merging merge bids (2 ancestors)

   f1: picking 'get' action

   f2: picking 'keep' action

  end of auction

  getting f1

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ hg up -qC

  $ hg merge -v --debug --config merge.preferancestor="*"

  note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd

  calculating bids for ancestor 0f6b37dbe527

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922

   f1: remote is newer -> g

   f2: versions differ -> m

  calculating bids for ancestor 40663881a6dd

  resolving manifests

   branchmerge: True, force: False, partial: False

   ancestor: 40663881a6dd, local: 3b08d01b0ab5+, remote: adfe50279922

   f1: versions differ -> m

   f2: remote unchanged -> k

  auction for merging merge bids (2 ancestors)

   list of bids for f1:

     remote is newer -> g

     versions differ -> m

   f1: picking 'get' action

   list of bids for f2:

     remote unchanged -> k

     versions differ -> m

   f2: picking 'keep' action

  end of auction

   f1: remote is newer -> g

  getting f1

   f2: remote unchanged -> k

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

Test the greatest common ancestor returning multiple changesets

  $ hg log -r 'heads(commonancestors(head()))'

  changeset:   1:0f6b37dbe527

  user:        test

  date:        Thu Jan 01 00:00:00 1970 +0000

  summary:     1 first change f1

  changeset:   2:40663881a6dd

  parent:      0:40494bf2444c

  user:        test

  date:        Thu Jan 01 00:00:00 1970 +0000

  summary:     2 first change f2

  $ cd ..

http://stackoverflow.com/questions/9350005/how-do-i-specify-a-merge-base-to-use-in-a-hg-merge/9430810

  $ hg init ancestor-merging

  $ cd ancestor-merging

  $ echo a > x

  $ hg commit -A -m a x

  $ hg update -q 0

  $ echo b >> x

  $ hg commit -m b

  $ hg update -q 0

  $ echo c >> x

  $ hg commit -qm c

  $ hg update -q 1

  $ hg merge -q --tool internal:local 2

  $ echo c >> x

  $ hg commit -m bc

  $ hg update -q 2

  $ hg merge -q --tool internal:local 1

  $ echo b >> x

  $ hg commit -qm cb

  $ hg merge --config merge.preferancestor='!'

  note: using 70008a2163f6 as ancestor of 0d355fdef312 and 4b8b546a3eef

        alternatively, use --config merge.preferancestor=b211bbc6eb3c

  merging x

  0 files updated, 1 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ cat x

  a

  c

  b

  c

  $ hg up -qC .

  $ hg merge --config merge.preferancestor=b211bbc6eb3c

  note: using b211bbc6eb3c as ancestor of 0d355fdef312 and 4b8b546a3eef

        alternatively, use --config merge.preferancestor=70008a2163f6

  merging x

  0 files updated, 1 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ cat x

  a

  b

  c

  b

  $ hg up -qC .

  $ hg merge -v --config merge.preferancestor="*"

  note: merging 0d355fdef312+ and 4b8b546a3eef using bids from ancestors 70008a2163f6 and b211bbc6eb3c

  calculating bids for ancestor 70008a2163f6

  resolving manifests

  calculating bids for ancestor b211bbc6eb3c

  resolving manifests

  auction for merging merge bids (2 ancestors)

   x: multiple bids for merge action:

    versions differ -> m

    versions differ -> m

   x: ambiguous merge - picked m action

  end of auction

  merging x

  0 files updated, 1 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ cat x

  a

  c

  b

  c

Verify that the old context ancestor works with / despite preferancestor:

  $ hg log -r 'ancestor(head())' --config merge.preferancestor=1 -T '{rev}\n'

  1