[vpython] Incorporate interpreter path/hash.

vpython/python/python_test.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 python
 
 import (
         "fmt"
         "os"
         "os/exec"
@@ skipping 105 matching lines @@
                 t.Fatalf("failed to get executable name: %s", err)
         }
 
         Convey(`A Python interpreter`, t, func() {
                 c := context.Background()
 
                 i := Interpreter{
                         Python: self,
                 }
 
+                Convey(`Testing hash`, func() {
+                        hash, err := i.Hash()
+                        So(err, ShouldBeNil)
+                        So(hash, ShouldNotEqual, "")
+
+                        t.Logf("Calculated interpreter hash: %s", hash)
+                })
+
                 Convey(`Testing IsolatedCommand`, func() {
                         cmd := i.IsolatedCommand(c, "foo", "bar")
                         So(cmd.Args, ShouldResemble, []string{self, "-B", "-E", "-s", "foo", "bar"})
                 })
 
         })
 }
 
 func TestInterpreterGetVersion(t *testing.T) {
         t.Parallel()
@@ skipping 52 matching lines @@
                 for _, tc := range versionFailures {
                         Convey(fmt.Sprintf(`Will fail to parse %q (%s)`, tc.output, tc.err), func() {
                                 versionString = tc.output
 
                                 _, err := i.GetVersion(c)
                                 So(err, ShouldErrLike, tc.err)
                         })
                 }
         })
 }