vpython: Leave "pip" and related tools.

vpython/venv/venv.go

 // Copyright 2017 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package venv
 
 import (
         "bytes"
         "encoding/json"
         "io/ioutil"
@@ skipping 11 matching lines @@
         "github.com/luci/luci-go/vpython/python"
         "github.com/luci/luci-go/vpython/wheel"
 
         "github.com/luci/luci-go/common/clock"
         "github.com/luci/luci-go/common/data/stringset"
         "github.com/luci/luci-go/common/errors"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/system/filesystem"
 )
 
+// EnvironmentVersion is an environment version string. It must advance each
+// time the layout of a VirtualEnv environment changes.
+const EnvironmentVersion = "v1"
+
 // ErrNotComplete is a sentinel error returned by AssertCompleteAndLoad to
 // indicate that the Environment is missing its completion flag.
 var ErrNotComplete = errors.New("environment is not complete")
 
 const (
         lockHeldDelay = 10 * time.Millisecond
 )
 
 // blocker is an fslock.Blocker implementation that sleeps lockHeldDelay in
 // between attempts.
@@ skipping 567 matching lines @@
                 "--find-links", pkgDir,
                 "--requirement", reqPath)
         attachOutputForLogging(c, logging.Debug, cmd)
         if err := cmd.Run(); err != nil {
                 return errors.Annotate(err).Reason("failed to install wheels").Err()
         }
         return nil
 }
 
 func (e *Env) finalize(c context.Context) error {
-        // Uninstall "pip" and "wheel", preventing (easy) augmentation of the
-        // environment.
-        if !e.Config.testPreserveInstallationCapability {
-                cmd := e.Interpreter().IsolatedCommand(c,
-                        "-m", "pip",
-                        "uninstall",
-                        "--quiet",
-                        "--yes",
-                        "pip", "wheel")
-                attachOutputForLogging(c, logging.Debug, cmd)
-                if err := cmd.Run(); err != nil {
-                        return errors.Annotate(err).Reason("failed to install wheels").Err()
-                }
-        }
-
         // Change all files to read-only, except:
         // - Our root directory, which must be writable in order to update our
         //   completion flag.
         // - Our environment stamp, which must be trivially re-writable.
         if !e.Config.testLeaveReadWrite {
                 err := filesystem.MakeReadOnly(e.Root, func(path string) bool {
                         switch path {
                         case e.Root, e.completeFlagPath:
                                 return false
                         default:
@@ skipping 107 matching lines @@
 // panic, since the locking state can no longer be determined.
 func mustReleaseLock(c context.Context, lock fslock.Handle, fn func() error) error {
         defer func() {
                 if err := lock.Unlock(); err != nil {
                         errors.Log(c, errors.Annotate(err).Reason("failed to release lock").Err())
                         panic(err)
                 }
         }()
         return fn()
 }