Add a new, simplified version of pipstrap.

tools/dev_constraints.txt

@@ -70,6 +70,7 @@ parso==0.7.0
 pathlib2==2.3.5
 pexpect==4.7.0
 pickleshare==0.7.5
+pip==20.2.4
 pkginfo==1.4.2
 pluggy==0.13.0
 ply==3.4
@@ -103,6 +104,7 @@ requests-toolbelt==0.8.0
 rsa==3.4.2
 s3transfer==0.3.1
 scandir==1.10.0
+setuptools==44.1.1
 simplegeneric==0.8.1
 singledispatch==3.4.0.3
 snowballstemmer==1.2.1
@@ -122,5 +124,6 @@ uritemplate==3.0.0
 virtualenv==16.6.2
 wcwidth==0.1.8
 websocket-client==0.56.0
+wheel==0.35.1
 wrapt==1.11.2
 zipp==0.6.0

tools/pipstrap.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+"""Uses pip to install or upgrade Python packaging tools.
+
+pip_install.py is used to accomplish this so packages like pip can be
+pinned the same way as our other packages.
+
+"""
+from __future__ import absolute_import
+
+import pip_install
+
+
+def main():
+    pkgs = 'pip setuptools wheel'.split()
+    pip_install.main(pkgs)
+
+
+if __name__ == '__main__':
+    main()