Implement PEP 477 - Backport ensurepip (PEP 453) to 2.7

* Backports ensurepip to the 2.7 branch
* Backports some of the improved documentation to the 2.7 branch.
* Adds a private backport of the 3.x mock library as test._mock_backport
  to enable saner testing of ensurepip.

Key Differences from 3.x:

* Ensurepip does not have any Makefile integration, specifically
  it is not ran by default in the Makefile.
* There is no venv module in 2.7, so downstream distributors can
  completely disable ensurepip, ideally with a message redirecting
  to the correct way to install pip.
* To match the ``python`` command in 2.7, ensurepip will install
  the unversioned ``pip`` command as well.
* No-op and hide --default-pip and add --no-default-pip to restore
  the 3.x behavor on 2.7.

1 files changed, 31 insertions, 0 deletions

diff --git a/Tools/scripts/checkpip.py b/Tools/scripts/checkpip.py
new file mode 100644
index 0000000..1b6049d
--- /dev/null
+++ b/Tools/scripts/checkpip.py
@@ -0,0 +1,31 @@
+#!/usr/bin/env python2
+"""
+Checks that the version of the projects bundled in ensurepip are the latest
+versions available.
+"""
+import ensurepip
+import json
+import urllib2
+import sys
+
+
+def main():
+    outofdate = False
+
+    for project, version in ensurepip._PROJECTS:
+        data = json.loads(urllib2.urlopen(
+            "https://pypi.python.org/pypi/{}/json".format(project),
+        ).read().decode("utf8"))
+        upstream_version = data["info"]["version"]
+
+        if version != upstream_version:
+            outofdate = True
+            print("The latest version of {} on PyPI is {}, but ensurepip "
+                  "has {}".format(project, upstream_version, version))
+
+    if outofdate:
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()