tests/test-merge-force.t

run-tests: move diff generation into TestResult

TestResult is the thing that captures all our test results. It's logical
for diff viewing to be handled there and not inside Test.

While writing this patch, it was discovered that Test.fail() was
printing redundant test result output. This has been removed.

Arguments controlling diffs have been removed from Test.__init__.

  $ hg init

  $ echo a > a
  $ hg ci -qAm 'add a'

  $ echo b > b
  $ hg ci -qAm 'add b'

  $ hg up -qC 0
  $ hg rm a
  $ hg ci -m 'rm a'
  created new head

  $ hg up -qC 1
  $ rm a

Local deleted a file, remote removed

Should fail, since there are deleted files:

  $ hg merge
  abort: uncommitted changes
  (use 'hg status' to list changes)
  [255]

Should succeed with --force:

  $ hg -v merge --force
  resolving manifests
  removing a
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

Should show 'a' as removed:

  $ hg status
  R a

  $ hg ci -m merge

Should not show 'a':

  $ hg manifest
  b