[errors] Greatly simplify common/errors package.

logdog/client/butlerlib/bootstrap/bootstrap.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 bootstrap
 
 import (
         "fmt"
 
         "github.com/luci/luci-go/client/environ"
@@ skipping 56 matching lines @@
                         return nil, fmt.Errorf("bootstrap: failed to create stream client [%s]: %s", p, err)
                 }
         }
 
         return bs, nil
 }
 
 func (bs *Bootstrap) initializeClient(v string, reg *streamclient.Registry) error {
         c, err := reg.NewClient(v)
         if err != nil {
-                return errors.Annotate(err).Reason("bootstrap: failed to create stream client [%(config)s]").D("config", v).Err()
+                return errors.Annotate(err, "bootstrap: failed to create stream client [%s]", v).Err()
         }
         bs.Client = c
         return nil
 }
 
 // Get loads a Bootstrap instance from the environment. It will return an error
 // if the bootstrap data is invalid, and will return ErrNotBootstrapped if the
 // current process is not bootstrapped.
 func Get() (*Bootstrap, error) {
         return getFromEnv(environ.Get(), streamclient.GetDefaultRegistry())
@@ skipping 23 matching lines @@
         if bs.Prefix == "" {
                 return "", errors.New("no prefix is configured")
         }
 
         paths := make([]types.StreamPath, len(streams))
         for i, s := range streams {
                 paths[i] = bs.Prefix.Join(types.StreamName(s.Properties().Name))
         }
         return bs.GetViewerURL(paths...)
 }