[errors] Greatly simplify common/errors package.

logdog/client/cli/subcommandQuery.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"
         "encoding/json"
         "io"
@@ skipping 59 matching lines @@
 
         // User-friendly: trim any leading or trailing slashes from the path.
         project, path, unified, err := a.splitPath(cmd.path)
         if err != nil {
                 log.WithError(err).Errorf(a, "Invalid path specifier.")
                 return 1
         }
 
         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
         }
 
         // Open our output file, if necessary.
         w := io.Writer(nil)
         switch cmd.out {
         case "-":
                 w = os.Stdout
         default:
                 f, err := os.OpenFile(cmd.out, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0643)
@@ skipping 173 matching lines @@
 }
 
 func (p *jsonQueryOutput) end() error {
         if err := p.ensureStart(); err != nil {
                 return err
         }
 
         _, err := p.WriteRune(']')
         return err
 }