Allow installation without history or metadata

[ionelmc]

Eg, allow this to just work (with pip install):

Collecting https://github.com/pytest-dev/pytest/archive/master.zip

  Downloading https://github.com/pytest-dev/pytest/archive/master.zip (654kB)

    Complete output from command python setup.py egg_info:



    Installed /tmp/pip-hFmzwC-build/.eggs/setuptools_scm-1.7.0-py2.7.egg

    Traceback (most recent call last):

      File "<string>", line 20, in <module>

      File "/tmp/pip-hFmzwC-build/setup.py", line 123, in <module>

        main()

      File "/tmp/pip-hFmzwC-build/setup.py", line 81, in main

        zip_safe=False,

      File "/opt/python/2.7.9/lib/python2.7/distutils/core.py", line 111, in setup

        _setup_distribution = dist = klass(attrs)

      File "/home/travis/build/pytest-dev/pytest-cov/.tox/2.7-28-37/lib/python2.7/site-packages/setuptools/dist.py", line 272, in __init__

        _Distribution.__init__(self,attrs)

      File "/opt/python/2.7.9/lib/python2.7/distutils/dist.py", line 287, in __init__

        self.finalize_options()

      File "/home/travis/build/pytest-dev/pytest-cov/.tox/2.7-28-37/lib/python2.7/site-packages/setuptools/dist.py", line 327, in finalize_options

        ep.load()(self, ep.name, value)

      File "build/bdist.linux-x86_64/egg/setuptools_scm/integration.py", line 17, in version_keyword

      File "build/bdist.linux-x86_64/egg/setuptools_scm/__init__.py", line 65, in get_version

      File "build/bdist.linux-x86_64/egg/setuptools_scm/__init__.py", line 34, in version_from_scm

    LookupError: setuptools-scm was unable to detect version for '/tmp/pip-hFmzwC-build'.



    Make sure you're not using GitHub's tarballs (or similar ones), as those don't contain the necessary metadata. Use PyPI's tarballs instead.

In this situation I don't think anyone cares about what the version is.