[cipd] Add subdir support to deployer.

cipd/client/cipd/client_test.go

 // Copyright 2015 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 cipd
 
 import (
         "bytes"
         "fmt"
         "io"
@@ skipping 711 matching lines @@
                         })
                         assertFile("file b", "test data")
                         So(findDeployed(tempDir), ShouldResemble, PinSliceBySubdir{"": PinSlice{b.Pin()}})
 
                         // Remove b.
                         actions, err = callEnsure(nil, nil)
                         So(err, ShouldBeNil)
                         So(actions, ShouldResemble, Actions{
                                 ToRemove: PinSlice{b.Pin()},
                         })
-                        So(findDeployed(tempDir), ShouldResemble, PinSliceBySubdir{"": PinSlice{}})
+                        So(findDeployed(tempDir), ShouldResemble, PinSliceBySubdir{})
 
                         // Install a1 and b.
                         actions, err = callEnsure([]local.PackageInstance{a1, b}, []local.PackageInstance{a1, b})
                         So(err, ShouldBeNil)
                         So(actions, ShouldResemble, Actions{
                                 ToInstall: PinSlice{a1.Pin(), b.Pin()},
                         })
                         assertFile("file a 1", "test data")
                         assertFile("file b", "test data")
                         So(findDeployed(tempDir), ShouldResemble, PinSliceBySubdir{"": PinSlice{a1.Pin(), b.Pin()}})
@@ skipping 191 matching lines @@
                                 w.Header().Add(k, s)
                         }
                 }
                 w.WriteHeader(exp.Status)
         }
         if exp.Reply != "" {
                 w.Write([]byte(exp.Reply))
         }
         s.index++
 }