Move to vendor

Signed-off-by: Olivier Gambier <olivier@docker.com>

vendor/github.com/bugsnag/bugsnag-go/errors/error.go

@@ -0,0 +1,90 @@
+// Package errors provides errors that have stack-traces.
+package errors
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"runtime"
+)
+
+// The maximum number of stackframes on any error.
+var MaxStackDepth = 50
+
+// Error is an error with an attached stacktrace. It can be used
+// wherever the builtin error interface is expected.
+type Error struct {
+	Err    error
+	stack  []uintptr
+	frames []StackFrame
+}
+
+// New makes an Error from the given value. If that value is already an
+// error then it will be used directly, if not, it will be passed to
+// fmt.Errorf("%v"). The skip parameter indicates how far up the stack
+// to start the stacktrace. 0 is from the current call, 1 from its caller, etc.
+func New(e interface{}, skip int) *Error {
+	var err error
+
+	switch e := e.(type) {
+	case *Error:
+		return e
+	case error:
+		err = e
+	default:
+		err = fmt.Errorf("%v", e)
+	}
+
+	stack := make([]uintptr, MaxStackDepth)
+	length := runtime.Callers(2+skip, stack[:])
+	return &Error{
+		Err:   err,
+		stack: stack[:length],
+	}
+}
+
+// Errorf creates a new error with the given message. You can use it
+// as a drop-in replacement for fmt.Errorf() to provide descriptive
+// errors in return values.
+func Errorf(format string, a ...interface{}) *Error {
+	return New(fmt.Errorf(format, a...), 1)
+}
+
+// Error returns the underlying error's message.
+func (err *Error) Error() string {
+	return err.Err.Error()
+}
+
+// Stack returns the callstack formatted the same way that go does
+// in runtime/debug.Stack()
+func (err *Error) Stack() []byte {
+	buf := bytes.Buffer{}
+
+	for _, frame := range err.StackFrames() {
+		buf.WriteString(frame.String())
+	}
+
+	return buf.Bytes()
+}
+
+// StackFrames returns an array of frames containing information about the
+// stack.
+func (err *Error) StackFrames() []StackFrame {
+	if err.frames == nil {
+		err.frames = make([]StackFrame, len(err.stack))
+
+		for i, pc := range err.stack {
+			err.frames[i] = NewStackFrame(pc)
+		}
+	}
+
+	return err.frames
+}
+
+// TypeName returns the type this error. e.g. *errors.stringError.
+func (err *Error) TypeName() string {
+	if _, ok := err.Err.(uncaughtPanic); ok {
+		return "panic"
+	}
+	return reflect.TypeOf(err.Err).String()
+}