bootstrap.py has a version and a --version argument

Replaces #204, fixes #30.

A date leads to less confusion than a version number separate
from buildout's own version number. Similarly, tracking buildout's version
number leads to bootstraps with a new version number but without changes or to
bootstraps with version number from an already-older buildout. So: a date is
best.

CHANGES.rst

@@ -22,6 +22,18 @@ Unreleased
   https://github.com/buildout/buildout/pull/222 .
   [lrowe]
 
+- Updated buildout's `travis-ci <https://travis-ci.org/buildout/buildout>`_
+  configuration so that tests run much quicker so that buildout is easier and
+  quicker to develop.
+  [reinout]
+
+- A new boostrap.py file is released (version 2015-07-01).
+
+- When bootstrapping, the ``develop-eggs/`` directory is first removed. This
+  prevents old left-over ``.egg-link`` files from breaking buildout's careful
+  package collection mechanism.
+  [reinout]
+
 - Bootstrap script now accepts ``--to-dir``. Setuptools is installed there. If
   already available there, it is reused. This can be used to bootstrap
   buildout without internet access. Similarly, a local ``ez_setup.py`` is used
@@ -33,14 +45,10 @@ Unreleased
   ``--version`` to pick a specific buildout version.
   [reinout]
 
-- Updated buildout's `travis-ci <https://travis-ci.org/buildout/buildout>`_
-  configuration so that tests run much quicker so that buildout is easier and
-  quicker to develop.
-  [reinout]
-
-- When bootstrapping, the ``develop-eggs/`` directory is first removed. This
-  prevents old left-over ``.egg-link`` files from breaking buildout's careful
-  package collection mechanism.
+- The bootstrap script now accepts ``--version`` which prints the bootstrap
+  version. This version is the date the bootstrap.py was last changed. A date
+  is handier or less confusing than either tracking zc.buildout's version or
+  having a separate bootstrap version number.
   [reinout]
 
 2.3.1 (2014-12-16)

bootstrap/bootstrap.py

@@ -25,6 +25,9 @@ import tempfile
 
 from optparse import OptionParser
 
+__version__ = '2015-07-01'
+# See zc.buildout's changelog if this version is up to date.
+
 tmpeggs = tempfile.mkdtemp(prefix='bootstrap-')
 
 usage = '''\
@@ -40,8 +43,9 @@ this script from going over the network.
 '''
 
 parser = OptionParser(usage=usage)
-parser.add_option("--buildout-version",
-                  help="Use a specific zc.buildout version")
+parser.add_option("--version",
+                  action="store_true", default=False,
+                  help=("Return bootstrap.py version."))
 parser.add_option("-t", "--accept-buildout-test-releases",
                   dest='accept_buildout_test_releases',
                   action="store_true", default=False,
@@ -59,6 +63,8 @@ parser.add_option("-f", "--find-links",
 parser.add_option("--allow-site-packages",
                   action="store_true", default=False,
                   help=("Let bootstrap.py use existing site packages"))
+parser.add_option("--buildout-version",
+                  help="Use a specific zc.buildout version")
 parser.add_option("--setuptools-version",
                   help="Use a specific setuptools version")
 parser.add_option("--setuptools-to-dir",
@@ -66,6 +72,9 @@ parser.add_option("--setuptools-to-dir",
                         "setuptools versions"))
 
 options, args = parser.parse_args()
+if options.version:
+    print("bootstrap.py version %s" % __version__)
+
 
 ######################################################################
 # load/install setuptools

src/zc/buildout/bootstrap.txt

@@ -159,3 +159,16 @@ specify the setuptools version, and to reuse the setuptools zipfile.
       '/sample/eggs/setuptools-14.3...egg',
       '/sample/eggs/zc.buildout-2.0.0...egg',
       ]...
+
+You can ask bootstrap.py for its version. This is really the day the last
+change was made. A date leads to less confusion than a version number separate
+from buildout's own version number. Similarly, tracking buildout's version
+number leads to bootstraps with a new version number but without changes or to
+bootstraps with version number from an already-older buildout. So: a date is
+best.
+
+    >>> print_('X'); print_(system(
+    ...     zc.buildout.easy_install._safe_arg(sys.executable)+' '+
+    ...     'bootstrap.py --version')); print_('X')
+    ... # doctest: +ELLIPSIS
+    X...2015...X