tests/test-diff-issue2761.t

templater: do not use index.partialmatch() directly to calculate shortest()

cl.index.partialmatch() isn't a drop-in replacement for cl._partialmatch().
It has no knowledge about hidden revisions, and it raises ValueError if a node
shorter than 4 chars is given. Instead, use index.partialmatch() through
cl._partialmatch(), which has no such problems and gives the identical result
with/without --pure.

The test output was sampled with --pure without this patch, which shows the
most correct result. However, we'll need to switch to using an unfiltered
changelog because _partialmatch() of a filtered changelog can be an order of
magnitude slower.

  (with hidden revisions)
  % hg log -R hg-committed -r0:20000 -T '{node|shortest}\n' --time > /dev/null
  (.^)  time: real 1.530 secs (user 1.480+0.000 sys 0.040+0.000)
  (.)   time: real 43.080 secs (user 43.060+0.000 sys 0.030+0.000)

Test issue2761

  $ hg init

  $ touch to-be-deleted
  $ hg add
  adding to-be-deleted
  $ hg ci -m first
  $ echo a > to-be-deleted
  $ hg ci -m second
  $ rm to-be-deleted
  $ hg diff -r 0

Same issue, different code path

  $ hg up -C
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ touch does-not-exist-in-1
  $ hg add
  adding does-not-exist-in-1
  $ hg ci -m third
  $ rm does-not-exist-in-1
  $ hg diff -r 1