[errors] Greatly simplify common/errors package.

logdog/client/butler/streamserver/namedPipe_posix.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.
 
 // +build darwin dragonfly freebsd linux netbsd openbsd
 
 package streamserver
 
 import (
         "net"
@@ skipping 14 matching lines @@
 // NewUNIXDomainSocketServer instantiates a new POSIX domain soecket server
 // instance.
 //
 // No resources are actually created until methods are called on the returned
 // server.
 func NewUNIXDomainSocketServer(ctx context.Context, path string) (StreamServer, error) {
         switch l := len(path); {
         case l == 0:
                 return nil, errors.New("cannot have empty path")
         case l > maxPOSIXNamedSocketLength:
-                return nil, errors.Reason("path exceeds maximum length %(max)d").
-                        D("path", path).
-                        D("max", maxPOSIXNamedSocketLength).
-                        Err()
+                return nil, errors.Reason("path exceeds maximum length %d", maxPOSIXNamedSocketLength).
+                        InternalReason("path(%s)", path).Err()
         }
 
         abs, err := filepath.Abs(path)
         if err != nil {
-                return nil, errors.Annotate(err).Reason("could not get absolute path of [%(path)s]").
-                        D("path", path).
-                        Err()
+                return nil, errors.Annotate(err, "could not get absolute path of [%s]", path).Err()
         }
         path = abs
 
         ctx = log.SetField(ctx, "namedPipePath", path)
         return &listenerStreamServer{
                 Context: ctx,
                 gen: func() (net.Listener, string, error) {
                         log.Infof(ctx, "Creating POSIX server socket Listener.")
 
                         // Cleanup any previous named pipe. We don't bother checking for the file
@@ skipping 41 matching lines @@
                                 log.ErrorKey: err,
                         }.Debugf(l, "Failed to remove named pipe file on Close().")
                 }
         }()
 
         if err := l.Listener.Close(); err != nil {
                 return err
         }
         return nil
 }