tests/test-narrow-update.t

revisions: allow "x123" to refer to nodeid prefix "123"

When resolving "123" to a revision, we try to interpret it as revnum
before we try to interpret it as a nodeid hex prefix. This can lead to
the shortest valid prefix being longer than necessary. This patch lets
us write such nodeids in a shorter form by prefixing them with "x"
instead of adding more hex digits until they're longer than the
longest decimal revnum.

On my hg repo with almost 69k revisions, turning this feature on saves
on average 0.4% on the average nodeid length. That clearly doesn't
justify this patch. However, it becomes more usefule when combined
with the earlier patches in this series that let you disambiguate
nodeid prefixes within a configured revset.

Note that we attempt to resolve symbols as nodeid prefixes after we've
exhausted all other posibilities, so this is a backwards compatible
change (only queries that would previously fail may now succeed).

I've still hidden this feature behind an experiemntal config option so
we can roll it back if needed.

Differential Revision: https://phab.mercurial-scm.org/D4041

  $ . "$TESTDIR/narrow-library.sh"

create full repo

  $ hg init master
  $ cd master
  $ echo init > init
  $ hg ci -Aqm 'initial'

  $ mkdir inside
  $ echo inside > inside/f1
  $ mkdir outside
  $ echo outside > outside/f1
  $ hg ci -Aqm 'add inside and outside'

  $ echo modified > inside/f1
  $ hg ci -qm 'modify inside'

  $ echo modified > outside/f1
  $ hg ci -qm 'modify outside'

  $ cd ..

  $ hg clone --narrow ssh://user@dummy/master narrow --include inside
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 2 changes to 1 files
  new changesets *:* (glob)
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrow
  $ hg debugindex -c
     rev linkrev nodeid       p1           p2
       0       0 9958b1af2add 000000000000 000000000000
       1       1 2db4ce2a3bfe 9958b1af2add 000000000000
       2       2 0980ee31a742 2db4ce2a3bfe 000000000000
       3       3 4410145019b7 0980ee31a742 000000000000

  $ hg update -q 0

Can update to revision with changes inside

  $ hg update -q 'desc("add inside and outside")'
  $ hg update -q 'desc("modify inside")'
  $ find *
  inside
  inside/f1
  $ cat inside/f1
  modified

Can update to revision with changes outside

  $ hg update -q 'desc("modify outside")'
  $ find *
  inside
  inside/f1
  $ cat inside/f1
  modified

Can update with a deleted file inside

  $ hg rm inside/f1
  $ hg update -q 'desc("modify inside")'
  $ hg update -q 'desc("modify outside")'
  $ hg update -q 'desc("initial")'
  $ hg update -q 'desc("modify inside")'

Can update with a moved file inside

  $ hg mv inside/f1 inside/f2
  $ hg update -q 'desc("modify outside")'
  $ hg update -q 'desc("initial")'
  $ hg update -q 'desc("modify inside")'