Installing collected packages: mozfile, blessings, mozlog, mozprofile, mozinfo, moznetwork, mozprocess, mozdevice, mozrunner, BeautifulSoup, mozinstall, mozversion, requests, six, configobj, mozregression
  Found existing installation: requests 2.9.1
    Not uninstalling requests at /home/rakhi/mozilla-central/python/requests, outside environment /home/rakhi/mozilla-central/obj-x86_64-unknown-linux-gnu/_virtualenv
Successfully installed BeautifulSoup-3.2.1 blessings-1.6 configobj-5.0.6 mozdevice-0.48 mozfile-1.2 mozinfo-0.9 mozinstall-1.12 mozlog-3.1 moznetwork-0.27 mozprocess-0.22 mozprofile-0.28 mozregression-1.0.2 mozrunner-6.11 mozversion-1.4 requests-2.7.0 six-1.10.0
You are using pip version 8.0.2, however version 8.1.0 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
Error running mach:

    ['artifact', 'install']

The error occurred in code that was called by the mach command. This is either
a bug in the called code itself or in the way that mach is calling it.

You should consider filing a bug for this issue.

If filing a bug, please include the full output of mach, including this error
message.

The details of the failure are as follows:

ValueError: Must provide path to exactly one of hg and git

  File "/home/rakhi/mozilla-central/python/mozbuild/mozbuild/mach_commands.py", line 1533, in artifact_install
    artifacts = self._make_artifacts(tree=tree, job=job, skip_cache=skip_cache)
  File "/home/rakhi/mozilla-central/python/mozbuild/mozbuild/mach_commands.py", line 1518, in _make_artifacts
    artifacts = Artifacts(tree, job, log=self.log, cache_dir=cache_dir, skip_cache=skip_cache, hg=hg, git=git)
  File "/home/rakhi/mozilla-central/python/mozbuild/mozbuild/artifacts.py", line 721, in __init__
    raise ValueError("Must provide path to exactly one of hg and git")
rakhi@rakhi-Inspiron-3542:~/mozilla-central$