Generated bootstrap script's install_pip isn't specific enough

[Pewpewarrows]

Steps to reproduce:

1. Generate a bootstrap script using virtualenv.create_bootstrap_script()
2. Populate a local directory of python packages to look at, include:
   • Pip itself
   • Any other package whose name begins with "pip-", such as https://github.com/nvie/pip-tools/
3. Attempt to create a virtualenv using the bootstrap script generate in step 1 as follows: python bootstrap.py ./ENV --never-download --extra-search-dir python_packages/

The install_pip function in the generated bootstrap file will incorrectly pick the other package that begins with "pip-", and treat it as the real pip package to install. Because of this, the real pip is never installed into the virtualenv, and thus the command is unavailable for use.

The regex for finding the package should be more specific, or it should run some sort of test to determine which package is the real pip.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Just add a comment if you want to keep it open. Thank you for your contributions.