[errors] Greatly simplify common/errors package.

logdog/client/cli/subcommandList.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 cli
 
 import (
         "bufio"
         "fmt"
         "os"
@@ skipping 42 matching lines @@
 
         if len(args) == 0 {
                 args = []string{""}
         }
 
         bio := bufio.NewWriter(os.Stdout)
         defer bio.Flush()
 
         coord, err := a.coordinatorClient("")
         if err != nil {
-                errors.Log(a, errors.Annotate(err).Reason("could not create Coordinator client").Err())
+                errors.Log(a, errors.Annotate(err, "could not create Coordinator client").Err())
                 return 1
         }
 
         for _, arg := range args {
                 arg = strings.TrimSpace(arg)
 
                 var (
                         project  cfgtypes.ProjectName
                         pathBase string
                         unified  bool
@@ skipping 73 matching lines @@
                         parts = append(parts, "archived")
                 }
 
                 if s.State.Purged {
                         parts = append(parts, "purged")
                 }
         }
 
         return strings.Join(parts, " ")
 }