tests/test-push-hook-lock.t

changegroup: flush the ui stdio buffers after adding a changegroup

This eliminates the following test failure on Windows, as well as a similar one
in evolve's test-wireproto.t.  See the previous patch for details on the
problem.

  --- e:/Projects/hg/tests/test-init.t
  +++ e:/Projects/hg/tests/test-init.t.err
  @@ -216,10 +216,10 @@
      * test                      0:08b9e9f63b32
     $ hg clone -e "python \"$TESTDIR/dummyssh\"" local ssh://user@dummy/remote-bookmarks
     searching for changes
  +  exporting bookmark test
     remote: adding changesets
     remote: adding manifests
     remote: adding file changes
     remote: added 1 changesets with 1 changes to 1 files
  -  exporting bookmark test
     $ hg -R remote-bookmarks bookmarks
        test                      0:08b9e9f63b32

  $ hg init 1

  $ echo '[ui]' >> 1/.hg/hgrc
  $ echo 'timeout = 10' >> 1/.hg/hgrc

  $ echo foo > 1/foo
  $ hg --cwd 1 ci -A -m foo
  adding foo

  $ hg clone 1 2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg clone 2 3
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cat <<EOF > $TESTTMP/debuglocks-pretxn-hook.sh
  > hg debuglocks
  > true
  > EOF
  $ echo '[hooks]' >> 2/.hg/hgrc
  $ echo "pretxnchangegroup.a = sh $TESTTMP/debuglocks-pretxn-hook.sh" >> 2/.hg/hgrc
  $ echo 'changegroup.push = hg push -qf ../1' >> 2/.hg/hgrc

  $ echo bar >> 3/foo
  $ hg --cwd 3 ci -m bar

  $ hg --cwd 3 push ../2
  pushing to ../2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  lock:  user *, process * (*s) (glob)
  wlock: free