Move multierror logic into luci-go.

common/errors/errors.go

Index: common/errors/errors.go
diff --git a/common/errors/errors.go b/common/errors/errors.go
index 3deb920326171543e6b5bda57141516d01e60c5b..ae4e885824dc1a0337a5991f559a2974e676aa2d 100644
--- a/common/errors/errors.go
+++ b/common/errors/errors.go
@@ -5,11 +5,15 @@
 package errors
 
 import (
+	"errors"
 	"fmt"
 	"path/filepath"
 	"runtime"
 )
 
+// New is a pass-through version of the standard errors.New function.

[M-A Ruel, 2015/07/22 18:20:36]

And what's the purpose?

[dnj, 2015/07/22 18:30:34]

Guess: one can import "...luci-go/common/errors" and still use "errors.New" in
their code.

[M-A Ruel, 2015/07/22 18:32:36]

Oh right, I forgot about the package name aliasing.

[iannucci, 2015/07/23 00:44:38]

Right... I figured this was easier than fixing the aliasing issue.

+var New = errors.New
+
 // MarkedError is the specific error type retuned by MakeMarkFn. It's designed
 // so that you can access the underlying object if needed.
 type MarkedError struct {