contrib/asv.conf.json

tests: make test-check-module-imports more robust

It failed for me without this in this way:
  tests/test-commandserver.t:19: relative import of stdlib module
  tests/test-lfs-serve.t:108: relative import of stdlib module
  tests/test-lfs-serve.t:255: relative import of stdlib module
  tests/test-lfs-serve.t:362: relative import of stdlib module
  tests/test-lfs-serve.t:406: relative import of stdlib module
  tests/test-lock.py:9: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-lrucachedict.py:5: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-match.py:5: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-remotefilelog-datapack.py:15: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-remotefilelog-histpack.py:14: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-simplekeyvaluefile.py:4: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-sshserver.py:6: imports not lexically sorted: silenttestrunner < unittest, True, True

This is because every module is considered a stdlib module, because
the stdlib_prefixes is /usr, and my repo is in /usr/local/home, which
means that sys.path contains a couple of
/usr/local/home/../hg/.. entries that count as "in the stdlib".
Fix this by preventing any path in sys.path that's inside the mercurial
source from being considered "in the stdlib".

Differential Revision: https://phab.mercurial-scm.org/D5294

{
    "version": 1,
    "project": "mercurial",
    "project_url": "https://mercurial-scm.org/",
    "repo": "..",
    "branches": ["default", "stable"],
    "environment_type": "virtualenv",
    "show_commit_url": "https://www.mercurial-scm.org/repo/hg/rev/",
    "benchmark_dir": "benchmarks",
    "env_dir": "../.asv/env",
    "results_dir": "../.asv/results",
    "html_dir": "../.asv/html"
}