$ mkdir t

  $ cd t

  $ hg init

  $ echo This is file a1 > a

  $ echo This is file b1 > b

  $ hg add a b

  $ hg commit -m "commit #0" -d "1000000 0"

  $ echo This is file b22 > b

  $ hg commit -m"comment #1" -d "1000000 0"

  $ hg update 0

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ rm b

  $ hg commit -A -m"comment #2" -d "1000000 0"

  removing b

  created new head

  $ mv a c

in theory, we shouldn't need the "-y" below, but it prevents

this test from hanging when "hg update" erroneously prompts the

user for "keep or delete"

should abort

  $ hg update -y 1

  abort: crosses branches (use 'hg merge' to merge or use 'hg update -C' to discard changes)

  $ mv c a

should succeed

  $ hg update -y 1

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ exit 0