tests/test-hghave.t

branchmap: check node against changelog instead of repo

Testing 'node in repo' requires constructing a changectx, which is a little
expensive.  Testing 'repo.changelog.hasnode(node)' is notably faster. This
saves 10-20ms off of every command, when testing a few thousand nodes from the
branch cache.

I considered changing the implementation of localrepository.__contains__ so
every place would benefit from the change, but since
localrepository.__contains__ uses changectx to check if the commit exists, it
means it supports a wider range of possible inputs (like revs, hashes, '.',
etc), so it seemed unnecessarily risky.

Testing that hghave does not crash when checking features

  $ hghave --test-features 2>/dev/null

Testing hghave extensibility for third party tools

  $ cat > hghaveaddon.py <<EOF
  > import hghave
  > @hghave.check("custom", "custom hghave feature")
  > def has_custom():
  >     return True
  > EOF

(invocation via run-tests.py)

  $ cat > test-hghaveaddon.t <<EOF
  > #require custom
  >   $ echo foo
  >   foo
  > EOF
  $ run-tests.py $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t
  .
  # Ran 1 tests, 0 skipped, 0 warned, 0 failed.

(invocation via command line)

  $ unset TESTDIR
  $ hghave custom

(terminate with exit code 2 at failure of importing hghaveaddon.py)

  $ rm hghaveaddon.*
  $ cat > hghaveaddon.py <<EOF
  > importing this file should cause syntax error
  > EOF

  $ hghave custom
  failed to import hghaveaddon.py from '.': invalid syntax (hghaveaddon.py, line 1)
  [2]