tests/test-merge8.t

tests: allow optional output when `test-lfs-server` is sent SIGTERM

I guess this has only ever been tested on Windows, but on macOS, the test was
failing with changes like:

    +++ /private/tmp/mercurial-ci/tests/test-lfs-test-server.t#git-server.err
    @@ -858,6 +858,7 @@
     (Restart the server in a different location so it no longer has the content)

       $ "$PYTHON" $RUNTESTDIR/killdaemons.py $DAEMON_PIDS
    +  $TESTTMP.sh: line 153: 38639 Terminated: 15          lfs-test-server > lfs-server.log 2>&1

     #if hg-server
       $ cat $TESTTMP/access.log $TESTTMP/errors.log

Test for changeset ba7c74081861
(update dirstate correctly for non-branchmerge updates)
  $ hg init a
  $ cd a
  $ echo a > a
  $ hg add a
  $ hg commit -m a
  $ cd ..
  $ hg clone a b
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd a
  $ hg mv a b
  $ hg commit -m move
  $ echo b >> b
  $ hg commit -m b
  $ cd ../b
  $ hg pull ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets e3c9b40284e1:772b37f1ca37
  (run 'hg update' to get a working copy)
  $ hg update
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cd ..