Revert of Removed virtualenv from depot_tools

bootstrap/virtualenv/docs/reference.rst

+Reference Guide
+===============
+
+``virtualenv`` Command
+----------------------
+
+.. _usage:
+
+Usage
+~~~~~
+
+:command:`virtualenv [OPTIONS] ENV_DIR`
+
+    Where ``ENV_DIR`` is an absolute or relative path to a directory to create
+    the virtual environment in.
+
+.. _options:
+
+Options
+~~~~~~~
+
+.. program: virtualenv
+
+.. option:: --version
+
+   show program's version number and exit
+
+.. option:: -h, --help
+
+   show this help message and exit
+
+.. option:: -v, --verbose
+
+   Increase verbosity.
+
+.. option:: -q, --quiet
+
+   Decrease verbosity.
+
+.. option:: -p PYTHON_EXE, --python=PYTHON_EXE
+
+   The Python interpreter to use, e.g.,
+   --python=python2.5 will use the python2.5 interpreter
+   to create the new environment.  The default is the
+   interpreter that virtualenv was installed with
+   (like ``/usr/bin/python``)
+
+.. option:: --clear
+
+   Clear out the non-root install and start from scratch.
+
+.. option:: --system-site-packages
+
+   Give the virtual environment access to the global
+   site-packages.
+
+.. option:: --always-copy
+
+   Always copy files rather than symlinking.
+
+.. option:: --relocatable
+
+   Make an EXISTING virtualenv environment relocatable.
+   This fixes up scripts and makes all .pth files relative.
+
+.. option:: --unzip-setuptools
+
+   Unzip Setuptools when installing it.
+
+.. option:: --no-setuptools
+
+   Do not install setuptools (or pip) in the new
+   virtualenv.
+
+.. option:: --no-pip
+
+   Do not install pip in the new virtualenv.
+
+.. option:: --extra-search-dir=DIR
+
+   Directory to look for setuptools/pip distributions in.
+   This option can be specified multiple times.
+
+.. option:: --prompt=PROMPT
+
+   Provides an alternative prompt prefix for this
+   environment.
+
+.. option:: --never-download
+
+   DEPRECATED. Retained only for backward compatibility.
+   This option has no effect. Virtualenv never downloads
+   pip or setuptools.
+
+.. option:: --no-site-packages
+
+   DEPRECATED. Retained only for backward compatibility.
+   Not having access to global site-packages is now the
+   default behavior.
+
+.. option:: --distribute
+.. option:: --setuptools
+
+   Legacy; now have no effect.  Before version 1.10 these could be used
+   to choose whether to install Distribute_ or Setuptools_ into the created
+   virtualenv. Distribute has now been merged into Setuptools, and the
+   latter is always installed.
+
+.. _Distribute: https://pypi.python.org/pypi/distribute
+.. _Setuptools: https://pypi.python.org/pypi/setuptools
+
+
+Configuration
+-------------
+
+Environment Variables
+~~~~~~~~~~~~~~~~~~~~~
+
+Each command line option is automatically used to look for environment
+variables with the name format ``VIRTUALENV_<UPPER_NAME>``. That means
+the name of the command line options are capitalized and have dashes
+(``'-'``) replaced with underscores (``'_'``).
+
+For example, to automatically use a custom Python binary instead of the
+one virtualenv is run with you can also set an environment variable::
+
+  $ export VIRTUALENV_PYTHON=/opt/python-3.3/bin/python
+  $ virtualenv ENV
+
+It's the same as passing the option to virtualenv directly::
+
+  $ virtualenv --python=/opt/python-3.3/bin/python ENV
+
+This also works for appending command line options, like ``--find-links``.
+Just leave an empty space between the passed values, e.g.::
+
+  $ export VIRTUALENV_EXTRA_SEARCH_DIR="/path/to/dists /path/to/other/dists"
+  $ virtualenv ENV
+
+is the same as calling::
+
+  $ virtualenv --extra-search-dir=/path/to/dists --extra-search-dir=/path/to/other/dists ENV
+
+.. envvar:: VIRTUAL_ENV_DISABLE_PROMPT
+
+   Any virtualenv created when this is set to a non-empty value will not have
+   it's :ref:`activate` modify the shell prompt.
+
+
+Configuration File
+~~~~~~~~~~~~~~~~~~
+
+virtualenv also looks for a standard ini config file. On Unix and Mac OS X
+that's ``$HOME/.virtualenv/virtualenv.ini`` and on Windows, it's
+``%APPDATA%\virtualenv\virtualenv.ini``.
+
+The names of the settings are derived from the long command line option,
+e.g. the option :option:`--python <-p>` would look like this::
+
+  [virtualenv]
+  python = /opt/python-3.3/bin/python
+
+Appending options like :option:`--extra-search-dir` can be written on multiple
+lines::
+
+  [virtualenv]
+  extra-search-dir =
+      /path/to/dists
+      /path/to/other/dists
+
+Please have a look at the output of :option:`--help <-h>` for a full list
+of supported options.
+
+
+Extending Virtualenv
+--------------------
+
+
+Creating Your Own Bootstrap Scripts
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+While this creates an environment, it doesn't put anything into the
+environment. Developers may find it useful to distribute a script
+that sets up a particular environment, for example a script that
+installs a particular web application.
+
+To create a script like this, call
+:py:func:`virtualenv.create_bootstrap_script`, and write the
+result to your new bootstrapping script.
+
+.. py:function:: create_bootstrap_script(extra_text)
+
+   Creates a bootstrap script from ``extra_text``, which is like
+   this script but with extend_parser, adjust_options, and after_install hooks.
+
+This returns a string that (written to disk of course) can be used
+as a bootstrap script with your own customizations. The script
+will be the standard virtualenv.py script, with your extra text
+added (your extra text should be Python code).
+
+If you include these functions, they will be called:
+
+.. py:function:: extend_parser(optparse_parser)
+
+   You can add or remove options from the parser here.
+
+.. py:function:: adjust_options(options, args)
+
+   You can change options here, or change the args (if you accept
+   different kinds of arguments, be sure you modify ``args`` so it is
+   only ``[DEST_DIR]``).
+
+.. py:function:: after_install(options, home_dir)
+
+   After everything is installed, this function is called. This
+   is probably the function you are most likely to use. An
+   example would be::
+
+       def after_install(options, home_dir):
+           if sys.platform == 'win32':
+               bin = 'Scripts'
+           else:
+               bin = 'bin'
+           subprocess.call([join(home_dir, bin, 'easy_install'),
+                            'MyPackage'])
+           subprocess.call([join(home_dir, bin, 'my-package-script'),
+                            'setup', home_dir])
+
+   This example immediately installs a package, and runs a setup
+   script from that package.
+
+Bootstrap Example
+~~~~~~~~~~~~~~~~~
+
+Here's a more concrete example of how you could use this::
+
+    import virtualenv, textwrap
+    output = virtualenv.create_bootstrap_script(textwrap.dedent("""
+    import os, subprocess
+    def after_install(options, home_dir):
+        etc = join(home_dir, 'etc')
+        if not os.path.exists(etc):
+            os.makedirs(etc)
+        subprocess.call([join(home_dir, 'bin', 'easy_install'),
+                         'BlogApplication'])
+        subprocess.call([join(home_dir, 'bin', 'paster'),
+                         'make-config', 'BlogApplication',
+                         join(etc, 'blog.ini')])
+        subprocess.call([join(home_dir, 'bin', 'paster'),
+                         'setup-app', join(etc, 'blog.ini')])
+    """))
+    f = open('blog-bootstrap.py', 'w').write(output)
+
+Another example is available `here`__.
+
+.. __: https://github.com/socialplanning/fassembler/blob/master/fassembler/create-venv-script.py