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

    searching for copies back to rev 3

  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

  merging f2

  my f2@3b08d01b0ab5+ other f2@adfe50279922 ancestor f2@40494bf2444c

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

  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon

  [1]

  $ head *

  ==> 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 update -C .' 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

    searching for copies back to rev 3

  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

    searching for copies back to rev 3

  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

   f1: picking 'get' action

   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)

  $ head *

  ==> 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

    searching for copies back to rev 3

  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

    searching for copies back to rev 3

  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

   f1: picking 'keep' action

   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)

  $ head *

  ==> 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

  $ 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

   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

    searching for copies back to rev 3

  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

    searching for copies back to rev 3

  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

   f1: picking 'get' action

   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)

  $ 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

   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

  $ hg log -r 'ancestor(head())' --config merge.preferancestor=2 -T '{rev}\n'

  2

  $ hg log -r 'ancestor(head())' --config merge.preferancestor=3 -T '{rev}\n'

  1

  $ hg log -r 'ancestor(head())' --config merge.preferancestor='1337 * - 2' -T '{rev}\n'

  2

  $ cd ..