ImportError: pkg_resources という名前のモジュールがありません

After upgrading python 2.6 to 2.7, this error is reported when executing scrapy and easy_install
curl https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py | python

Reinstall setuptools to fix it

Traceback (most recent call last):
  File "/var/www/mydir/virtualenvs/dev/bin/pip", line 5, in <module>
    from pkg_resources import load_entry_point
ImportError: No module named pkg_resources

curl https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py | python

Reinstall setuptools to fix it

Traceback (most recent call last):

  File "/var/www/mydir/virtualenvs/dev/bin/pip", line 5, in <module>
    from pkg_resources import load_entry_point
ImportError: No module named pkg_resources