tests/test-update-renames.t

tests: pull common http server setup out of individual tests

There are currently two different tests using roughly the same code to
create temporary scripts acting as HTTP servers. As there is going to
be at least one more in an upcoming change, factor those out in a
standalone dumbhttp.py script.

Test update logic when there are renames

Update with local changes across a file rename

  $ hg init

  $ echo a > a
  $ hg add a
  $ hg ci -m a

  $ hg mv a b
  $ hg ci -m rename

  $ echo b > b
  $ hg ci -m change

  $ hg up -q 0

  $ echo c > a

  $ hg up
  merging a and b to b
  warning: conflicts during merge.
  merging b incomplete! (edit conflicts, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]