tests: add criss cross merging tests whose behavior need to be fixed

Merging two changesets can mark a file as removed post merge. However, in some
cases, a user might not want to remove that file and they revert the removal
back and commit the merge. All this works perfectly well.

However, when we do criss-cross merges with such merge where user explicitly
choose to revert the removal with one where another user choose the removal,
we does not get any conflict.

The intent here is conflicting and merge should result in conflicts. One user
merged and want to keep the file while other user merged and want to remove the
file. Merging those merges should result in conflicts.

This patch adds test cases for these cases.

Differential Revision: https://phab.mercurial-scm.org/D8939

tests/test-merge-criss-cross.t

@@ -1,471 +1,693 b''
 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
   $ 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 ..
 
   $ hg init issue5020
   $ cd issue5020
 
   $ echo a > noop
   $ hg ci -qAm initial
 
   $ echo b > noop
   $ hg ci -qAm 'uninteresting change'
 
   $ hg up -q 0
   $ mkdir d1
   $ echo a > d1/a
   $ echo b > d1/b
   $ hg ci -qAm 'add d1/a and d1/b'
 
   $ hg merge -q 1
   $ hg rm d1/a
   $ hg mv -q d1 d2
   $ hg ci -qm 'merge while removing d1/a and moving d1/b to d2/b'
 
   $ hg up -q 1
   $ hg merge -q 2
   $ hg ci -qm 'merge (no changes while merging)'
   $ hg log -G -T '{rev}:{node|short} {desc}'
   @    4:c0ef19750a22 merge (no changes while merging)
   |\
   +---o  3:6ca01f7342b9 merge while removing d1/a and moving d1/b to d2/b
   | |/
   | o  2:154e6000f54e add d1/a and d1/b
   | |
   o |  1:11b5b303e36c uninteresting change
   |/
   o  0:7b54db1ebf33 initial
   
   $ hg merge 3 --debug
   note: merging c0ef19750a22+ and 6ca01f7342b9 using bids from ancestors 11b5b303e36c and 154e6000f54e
   
   calculating bids for ancestor 11b5b303e36c
   resolving manifests
    branchmerge: True, force: False, partial: False
    ancestor: 11b5b303e36c, local: c0ef19750a22+, remote: 6ca01f7342b9
    d2/b: remote created -> g
   
   calculating bids for ancestor 154e6000f54e
     unmatched files in other:
      d2/b
     all copies found (* = to merge, ! = divergent, % = renamed and deleted):
      on remote side:
       src: 'd1/b' -> dst: 'd2/b' 
     checking for directory renames
      discovered dir src: 'd1/' -> dst: 'd2/'
   resolving manifests
    branchmerge: True, force: False, partial: False
    ancestor: 154e6000f54e, local: c0ef19750a22+, remote: 6ca01f7342b9
    d1/a: other deleted -> r
    d1/b: other deleted -> r
    d2/b: remote created -> g
   
   auction for merging merge bids (2 ancestors)
    list of bids for d1/a:
      other deleted -> r
    d1/a: consensus for r
    list of bids for d1/b:
      other deleted -> r
    d1/b: consensus for r
    list of bids for d2/b:
      remote created -> g
      remote created -> g
    d2/b: consensus for g
   end of auction
   
    d1/a: other deleted -> r
   removing d1/a
    d1/b: other deleted -> r
   removing d1/b
    d2/b: remote created -> g
   getting d2/b
   1 files updated, 0 files merged, 2 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
+
+
+Check that removal reversion does not go unotified
+==================================================
+
+On a merge, a file can be removed and user can revert that removal. This means
+user has made an explicit choice of keeping the file or reverting the removal
+even though the merge algo wanted to remove it.
+Based on this, when we do criss cross merges, merge algorithm should not again
+choose to remove the file as in one of the merges, user made an explicit choice
+to revert the removal.
+Following test cases demonstrate how merge algo does not take in account
+explicit choices made by users to revert the removal and on criss-cross merging
+removes the file again.
+
+"Simple" case where the filenode changes
+----------------------------------------
+
+  $ cd ..
+  $ hg init criss-cross-merge-reversal-with-update
+  $ cd criss-cross-merge-reversal-with-update
+  $ echo the-file > the-file
+  $ echo other-file > other-file
+  $ hg add the-file other-file
+  $ hg ci -m 'root-commit'
+  $ echo foo >> the-file
+  $ echo bar >> other-file
+  $ hg ci -m 'updating-both-file'
+  $ hg up 'desc("root-commit")'
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg rm the-file
+  $ hg ci -m 'delete-the-file'
+  created new head
+  $ hg log -G -T '{node|short} {desc}\n'
+  @  7801bc9b9899 delete-the-file
+  |
+  | o  9b610631ab29 updating-both-file
+  |/
+  o  955800955977 root-commit
+  
+
+Do all the merge combination (from the deleted or the update side × keeping and deleting the file
+
+  $ hg update 'desc("delete-the-file")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge 'desc("updating-both-file")' -t :local
+  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "merge-deleting-the-file-from-deleted"
+  $ hg manifest
+  other-file
+
+  $ hg update 'desc("updating-both-file")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge 'desc("delete-the-file")' -t :other
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "merge-deleting-the-file-from-updated"
+  created new head
+  $ hg manifest
+  other-file
+
+  $ hg update 'desc("delete-the-file")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge 'desc("updating-both-file")' -t :other
+  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "merge-keeping-the-file-from-deleted"
+  created new head
+  $ hg manifest
+  other-file
+  the-file
+
+  $ hg update 'desc("updating-both-file")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge 'desc("delete-the-file")' -t :local
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m "merge-keeping-the-file-from-updated"
+  created new head
+  $ hg manifest
+  other-file
+  the-file
+
+There the resulting merge together (leading to criss cross situation). Check
+the conflict is properly detected.
+
+(merging two deletion together → no conflict)
+
+  $ hg update --clean 'desc("merge-deleting-the-file-from-deleted")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-deleting-the-file-from-updated")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-deleting-the-file-from-deleted")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-keeping-the-file-from-deleted")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+  the-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-deleting-the-file-from-deleted")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-keeping-the-file-from-updated")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+  the-file
+
+(merging two deletion together → no conflict)
+
+  $ hg update --clean 'desc("merge-deleting-the-file-from-updated")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-deleting-the-file-from-deleted")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-deleting-the-file-from-updated")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-keeping-the-file-from-deleted")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+  the-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-deleting-the-file-from-updated")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-keeping-the-file-from-updated")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+  the-file
+
+(merging two "keeping" together → no conflict)
+
+  $ hg update --clean 'desc("merge-keeping-the-file-from-updated")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-keeping-the-file-from-deleted")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+  the-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-keeping-the-file-from-updated")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-deleted-the-file-from-deleted")'
+  abort: empty revision set
+  [255]
+  $ ls -1
+  other-file
+  the-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-keeping-the-file-from-updated")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-deleting-the-file-from-updated")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+
+(merging two "keeping" together → no conflict)
+
+  $ hg update --clean 'desc("merge-keeping-the-file-from-deleted")'
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-keeping-the-file-from-updated")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file
+  the-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-keeping-the-file-from-deleted")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-deleted-the-file-from-deleted")'
+  abort: empty revision set
+  [255]
+  $ ls -1
+  other-file
+  the-file
+
+(merging a deletion with keeping → conflict)
+BROKEN: this should result in conflict
+
+  $ hg update --clean 'desc("merge-keeping-the-file-from-deleted")'
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge          'desc("merge-deleting-the-file-from-updated")'
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ ls -1
+  other-file