tests/test-issue1089.t

rust: Add a Timestamp struct instead of abusing Duration

`SystemTime` would be the standard library type semantically appropriate
instead of `Duration`.

But since the value is coming from Python as a plain integer and used in
dirstate packing code as an integer, let’s make a type that contains a single
integer instead of using one with sub-second precision.

Differential Revision: https://phab.mercurial-scm.org/D10485

https://bz.mercurial-scm.org/1089

  $ hg init
  $ mkdir a
  $ echo a > a/b
  $ hg ci -Am m
  adding a/b

  $ hg rm a
  removing a/b
  $ hg ci -m m a

  $ mkdir a b
  $ echo a > a/b
  $ hg ci -Am m
  adding a/b

  $ hg rm a
  removing a/b
  $ cd b

Relative delete:

  $ hg ci -m m ../a

  $ cd ..