Attempt to go Python3-only

Ubuntu 20.04 no longer really supports Python 2, so we'd have to fork
the packaging code if we wanted to keep support for Python 2
elsewhere.  Given that Python 3 has been around for a more than a
decade and that Python 2 was formally EOLed more than six months ago
as of this writing, this seems like an unnecessary complication.

The biggest change is rewriting the Homebrew formula for Python 3.

4 files changed, 15 insertions, 16 deletions

diff --git a/scripts/build-debian-control-files.py b/scripts/build-debian-control-files.py
index c06055d..46958ea 100755
--- a/scripts/build-debian-control-files.py
+++ b/scripts/build-debian-control-files.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import subprocess
 import argparse
@@ -25,23 +25,18 @@ Priority: optional
 Standards-Version: 3.9.6
 Build-Depends: debhelper (>= 9),
                dh-python,
-               python (>= 2.7),
-               python-yaml,
+               python3-yaml,
                python3
 Homepage: http://trac.cryptech.is/wiki
 
 Package: {args.package}
 Architecture: any
-Depends: python,
-         python-serial (>= 3.0),
-         python-tornado (>= 4.0),
-         python-crypto,
-         python3,
+Depends: python3,
          python3-serial (>= 3.0),
          python3-tornado (>= 4.0),
          python3-crypto,
          ${{misc:Depends}},
-         ${{python:Depends}},
+         ${{python3:Depends}},
          ${{shlibs:Depends}}
 {conflicts}\
 Description: Cryptech Project open-source cryptographic software and firmware.
diff --git a/scripts/build-firmware-package.py b/scripts/build-firmware-package.py
index 9a58970..659a63f 100755
--- a/scripts/build-firmware-package.py
+++ b/scripts/build-firmware-package.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import subprocess
 import tempfile
diff --git a/scripts/build-homebrew-formula.py b/scripts/build-homebrew-formula.py
index 54cdcae..852b4b6 100755
--- a/scripts/build-homebrew-formula.py
+++ b/scripts/build-homebrew-formula.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Yes, this is a Python program writing a Ruby program.
 
@@ -32,7 +32,7 @@ template = '''\
 # code, however, is what Homebrew considers "bindings", so we install
 # those where user scripts as well as our own can find them...then we
 # add a symlink so that our scripts can find our bindings regardless
-# of which copy of Python 2.7 Homebrew decides we should use this week.
+# of which copy of Python Homebrew decides we should use this week.
 #
 # We have to build our own software before installing our Python code,
 # because at least one of the Python modules we install
@@ -54,6 +54,8 @@ class {classname} < Formula
   url      "{url}"
   sha256   "{sha256}"
 
+  depends_on "python@3.8"
+
 {conflicts}
 
   resource "pyserial" do
@@ -88,11 +90,13 @@ class {classname} < Formula
 
   def install
 
-    ENV.prepend_create_path "PYTHONPATH", libexec/"vendor/lib/python2.7/site-packages"
+    xy = Language::Python.major_minor_version "python3"
+
+    ENV.prepend_create_path "PYTHONPATH", libexec/"vendor/lib/python#{xy}/site-packages"
 
     resources.each do |r|
       r.stage do
-        system "python", *Language::Python.setup_install_args(libexec/"vendor")
+        system "python3", *Language::Python.setup_install_args(libexec/"vendor")
       end
     end
 
@@ -103,7 +107,7 @@ class {classname} < Formula
     system "python", *Language::Python.setup_install_args(prefix)
     bin.env_script_all_files(libexec/"bin", :PYTHONPATH => ENV["PYTHONPATH"])
 
-    ln_s lib/"python2.7/site-packages/cryptech", libexec/"vendor/lib/python2.7/site-packages/cryptech"
+    ln_s lib/"python#{xy}/site-packages/cryptech", libexec/"vendor/lib/python#{xy}/site-packages/cryptech"
 
     share.install "cryptech-alpha-firmware.tar.gz"
     lib.install   "sw/pkcs11/libcryptech-pkcs11.dylib"
diff --git a/scripts/build-shadow-tree.py b/scripts/build-shadow-tree.py
index 378797f..0f3a4a1 100755
--- a/scripts/build-shadow-tree.py
+++ b/scripts/build-shadow-tree.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Create a symlink build tree like the old X11 project "lndir" program.
 #