RevisionSpec_dwim uses in_history to check validity of revspec

[Jelmer Vernooij]

RevisionSpec_dwim uses in_history to check validity of revspec. This means that it will potentially scan the entire branch history to see if a revspec is valid. It should avoid this, and simply check if the returned revision info is valid.

[Jelmer Vernooij (jelmer)]

gwenhwyvar:~/src/samba/trunk% time bzr log -rgit:d12309dc1ace834e6b49a275e6b52ed0e864a651
------------------------------------------------------------
revno: 22808
git commit: d12309dc1ace834e6b49a275e6b52ed0e864a651
committer: Andrew Tridgell <email address hidden>
timestamp: Tue 2011-10-04 15:08:56 +1100
message:
  s4-partition: allow creation of uninstantiated partitions

  this is needed for a subdomain join by a new NC. The NC is initially
  uninstantiated
bzr log -rgit:d12309dc1ace834e6b49a275e6b52ed0e864a651 0.48s user 0.05s system 98% cpu 0.545 total
gwenhwyvar:~/src/samba/trunk% time bzr log -rd12309dc1ace834e6b49a275e6b52ed0e864a651
------------------------------------------------------------
revno: 22808
git commit: d12309dc1ace834e6b49a275e6b52ed0e864a651
committer: Andrew Tridgell <email address hidden>
timestamp: Tue 2011-10-04 15:08:56 +1100
message:
  s4-partition: allow creation of uninstantiated partitions

  this is needed for a subdomain join by a new NC. The NC is initially
  uninstantiated
bzr log -rd12309dc1ace834e6b49a275e6b52ed0e864a651 3.12s user 0.07s system 98% cpu 3.243 total