xbuddy: convert to python3 only

All users of these modules are python3 only already.

BUG=chromium:997354
TEST=`./run_tests` passes

Change-Id: I37ef56535b43d46ddebfaf02c9b0c6157d72007b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2643374
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
diff --git a/lib/xbuddy/__init__.py b/lib/xbuddy/__init__.py
index e69de29..6f6aab1 100644
--- a/lib/xbuddy/__init__.py
+++ b/lib/xbuddy/__init__.py
@@ -0,0 +1,8 @@
+# Copyright 2020 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import sys
+
+
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
diff --git a/lib/xbuddy/build_artifact_unittest b/lib/xbuddy/build_artifact_unittest
deleted file mode 120000
index ef3e37b..0000000
--- a/lib/xbuddy/build_artifact_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/xbuddy/common_util_unittest b/lib/xbuddy/common_util_unittest
deleted file mode 120000
index ef3e37b..0000000
--- a/lib/xbuddy/common_util_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/xbuddy/downloader_unittest b/lib/xbuddy/downloader_unittest
deleted file mode 120000
index ef3e37b..0000000
--- a/lib/xbuddy/downloader_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/xbuddy/xbuddy_unittest b/lib/xbuddy/xbuddy_unittest
deleted file mode 120000
index ef3e37b..0000000
--- a/lib/xbuddy/xbuddy_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../../scripts/wrapper.py
\ No newline at end of file
diff --git a/scripts/run_tests.py b/scripts/run_tests.py
index 8cb47ea..32b96bf 100644
--- a/scripts/run_tests.py
+++ b/scripts/run_tests.py
@@ -75,12 +75,6 @@
     # Tests that need to run inside the chroot.
     'lib/cros_test_lib_unittest': INSIDE,
     'lib/operation_unittest': INSIDE,
-
-    # These require 3rd party modules that are in the chroot.
-    'lib/xbuddy/build_artifact_unittest': INSIDE,
-    'lib/xbuddy/common_util_unittest': INSIDE,
-    'lib/xbuddy/downloader_unittest': INSIDE,
-    'lib/xbuddy/xbuddy_unittest': INSIDE,
 }
 
 SLOW_TESTS = {