tests/test-merge7.t

phabricator: use Phabricator's last node information

This makes it more strict when checking whether or not we should update a
Differential Revision. For example,

  a) Alice updates D1 to content 1.
  b) Bob updates D1 to content 2.
  c) Alice tries to update D1 to content 1.

Previously, `c)` will do nothing because `phabsend` detects the patch is not
changed. A more correct behavior is to override Bob's update here, hence the
patch.

This also makes it possible to return a reaonsable "last node" when there is
no tags but only `Differential Revision` commit messages.

Test Plan:
```
for i in A B C; do echo $i > $i; hg ci -m $i -A $i; done

hg phabsend 0::
# D40: created
# D41: created
# D42: created

echo 3 >> C; hg amend; hg phabsend .
# D42: updated

hg tag --local --hidden -r 2 -f D42
# move tag to the previous version

hg phabsend .
# D42: skipped (previously it would be "updated")

rm -rf .hg; hg init
hg phabread --stack D42 | hg import -
hg phabsend .
# D42: updated
hg tag --local --remove D42
hg commit --amend
hg phabsend .
# D42: updated (no new diff uploaded, previously it will upload a new diff)
```

The old diff object is now returned, which could be useful in the next
patch.

Differential Revision: https://phab.mercurial-scm.org/D121

initial
  $ hg init test-a
  $ cd test-a
  $ cat >test.txt <<"EOF"
  > 1
  > 2
  > 3
  > EOF
  $ hg add test.txt
  $ hg commit -m "Initial"

clone
  $ cd ..
  $ hg clone test-a test-b
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

change test-a
  $ cd test-a
  $ cat >test.txt <<"EOF"
  > one
  > two
  > three
  > EOF
  $ hg commit -m "Numbers as words"

change test-b
  $ cd ../test-b
  $ cat >test.txt <<"EOF"
  > 1
  > 2.5
  > 3
  > EOF
  $ hg commit -m "2 -> 2.5"

now pull and merge from test-a
  $ hg pull ../test-a
  pulling from ../test-a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg merge
  merging test.txt
  warning: conflicts while merging test.txt! (edit, then use 'hg resolve --mark')
  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]
resolve conflict
  $ cat >test.txt <<"EOF"
  > one
  > two-point-five
  > three
  > EOF
  $ rm -f *.orig
  $ hg resolve -m test.txt
  (no more unresolved files)
  $ hg commit -m "Merge 1"

change test-a again
  $ cd ../test-a
  $ cat >test.txt <<"EOF"
  > one
  > two-point-one
  > three
  > EOF
  $ hg commit -m "two -> two-point-one"

pull and merge from test-a again
  $ cd ../test-b
  $ hg pull ../test-a
  pulling from ../test-a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg merge --debug
    searching for copies back to rev 1
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 96b70246a118, local: 50c3a7e29886+, remote: 40d11a4173a8
   preserving test.txt for resolve of test.txt
  starting 4 threads for background file closing (?)
   test.txt: versions differ -> m (premerge)
  picked tool ':merge' for test.txt (binary False symlink False changedelete False)
  merging test.txt
  my test.txt@50c3a7e29886+ other test.txt@40d11a4173a8 ancestor test.txt@96b70246a118
   test.txt: versions differ -> m (merge)
  picked tool ':merge' for test.txt (binary False symlink False changedelete False)
  my test.txt@50c3a7e29886+ other test.txt@40d11a4173a8 ancestor test.txt@96b70246a118
  warning: conflicts while merging test.txt! (edit, then use 'hg resolve --mark')
  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]

  $ cat test.txt
  one
  <<<<<<< working copy: 50c3a7e29886 - test: Merge 1
  two-point-five
  =======
  two-point-one
  >>>>>>> merge rev:    40d11a4173a8 - test: two -> two-point-one
  three

  $ hg debugindex test.txt
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       7  .....       0 01365c4cca56 000000000000 000000000000 (re)
       1         7       9  .....       1 7b013192566a 01365c4cca56 000000000000 (re)
       2        16      15  .....       2 8fe46a3eb557 01365c4cca56 000000000000 (re)
       3        31      2.  .....       3 fc3148072371 7b013192566a 8fe46a3eb557 (re)
       4        5.      25  .....       4 d40249267ae3 8fe46a3eb557 000000000000 (re)

  $ hg log
  changeset:   4:40d11a4173a8
  tag:         tip
  parent:      2:96b70246a118
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     two -> two-point-one
  
  changeset:   3:50c3a7e29886
  parent:      1:d1e159716d41
  parent:      2:96b70246a118
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Merge 1
  
  changeset:   2:96b70246a118
  parent:      0:b1832b9d912a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Numbers as words
  
  changeset:   1:d1e159716d41
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2.5
  
  changeset:   0:b1832b9d912a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Initial
  

  $ cd ..