tests/test-debugrename.t

tests: add a wrapper to run fsmonitor tests

This script does a bunch of non-trivial configuration work: in particular, it
sets up an isolated instance of Watchman which isn't affected by global state
and can be torn down on completion.

This script also sets the HGFSMONITOR_TESTS environment variable, which hghave
will use in the next patch to allow gating on whether fsmonitor is enabled.

With fsmonitor enabled, there appear to be a number of failures in the test
suite. It's not yet clear to me why they're happening, but if someone would
like to jump in and fix some of them I hope this will be helpful for that.

  $ hg init
  $ echo a > a
  $ hg ci -Am t
  adding a

  $ hg mv a b
  $ hg ci -Am t1
  $ hg debugrename b
  b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3

  $ hg mv b a
  $ hg ci -Am t2
  $ hg debugrename a
  a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980

  $ hg debugrename --rev 1 b
  b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3