Ensure (de)compressor is always closed.

common/isolatedclient/isolatedclient.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 isolatedclient
 
 import (
         "bytes"
         "encoding/base64"
         "errors"
@@ skipping 331 matching lines @@
         pr, pw := io.Pipe()
         go func() {
                 // The compressor itself is not thread safe.
                 compressor, err := isolated.GetCompressor(pw)
                 if err != nil {
                         pw.CloseWithError(err)
                         return
                 }
                 buf := make([]byte, 4096)
                 if _, err := io.CopyBuffer(compressor, src, buf); err != nil {
+                        compressor.Close()
                         pw.CloseWithError(err)
                         return
                 }
                 pw.CloseWithError(compressor.Close())
         }()
 
         return &compressed{pr, src}
 }