tests/test-merge2.t

rust: upgrade minimum `rayon` dependency

The 1.6.0 and 1.6.1 releases fixes a soundness issue and a performance issue
that are both important to us, since both correctness and performance are
paramount in the Rust extensions.

  $ hg init t
  $ cd t
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ rm b
  $ hg update 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo This is file b2 > b
  $ hg add b
  $ hg commit -m "commit #2"
  created new head
  $ cd ..; rm -r t

  $ mkdir t
  $ cd t
  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ rm b
  $ hg update 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo This is file b2 > b
  $ hg commit -A -m "commit #2"
  adding b
  created new head
  $ cd ..; rm -r t

  $ hg init t
  $ cd t
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ rm b
  $ hg remove b
  $ hg update 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo This is file b2 > b
  $ hg commit -A -m "commit #2"
  adding b
  created new head

  $ hg merge 'wdir()'
  abort: merging with the working copy has no effect
  [10]

  $ cd ..