tests/test-merge9.t

hardlink: check directory's st_dev when copying files

Previously, when copying a file, copyfiles will compare src's st_dev with
dirname(dst)'s st_dev, to decide whether to enable hardlink or not.

That could have issues on Linux's overlayfs, where stating directories could
result in different st_dev from st_dev of stating files, even if both the
directories and the files exist in the overlay's upperdir.

This patch fixes it by checking dirname(src) instead. It's more consistent
because we are checking directories for both src and dest.

That fixes test-hardlinks.t running on common Docker setups.

test that we don't interrupt the merge session if
a file-level merge failed

  $ hg init repo
  $ cd repo

  $ echo foo > foo
  $ echo a > bar
  $ hg ci -Am 'add foo'
  adding bar
  adding foo

  $ hg mv foo baz
  $ echo b >> bar
  $ echo quux > quux1
  $ hg ci -Am 'mv foo baz'
  adding quux1

  $ hg up -qC 0
  $ echo >> foo
  $ echo c >> bar
  $ echo quux > quux2
  $ hg ci -Am 'change foo'
  adding quux2
  created new head

test with the rename on the remote side
  $ HGMERGE=false hg merge
  merging bar
  merging foo and baz to baz
  merging bar failed!
  1 files updated, 1 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]
  $ hg resolve -l
  U bar
  R baz

test with the rename on the local side
  $ hg up -C 1
  3 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ HGMERGE=false hg merge
  merging bar
  merging baz and foo to baz
  merging bar failed!
  1 files updated, 1 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]

show unresolved
  $ hg resolve -l
  U bar
  R baz

unmark baz
  $ hg resolve -u baz

show
  $ hg resolve -l
  U bar
  U baz
  $ hg st
  M bar
  M baz
  M quux2
  ? bar.orig

re-resolve baz
  $ hg resolve baz
  merging baz and foo to baz

after resolve
  $ hg resolve -l
  U bar
  R baz

resolve all warning
  $ hg resolve
  abort: no files or directories specified
  (use --all to re-merge all unresolved files)
  [255]

resolve all
  $ hg resolve -a
  merging bar
  warning: conflicts while merging bar! (edit, then use 'hg resolve --mark')
  [1]

after
  $ hg resolve -l
  U bar
  R baz

  $ cd ..