--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vendor/github.com/pkg/errors/go113.go	Sun Feb 16 18:54:01 2020 +0100
@@ -0,0 +1,38 @@
+// +build go1.13
+
+package errors
+
+import (
+	stderrors "errors"
+)
+
+// Is reports whether any error in err's chain matches target.
+//
+// The chain consists of err itself followed by the sequence of errors obtained by
+// repeatedly calling Unwrap.
+//
+// An error is considered to match a target if it is equal to that target or if
+// it implements a method Is(error) bool such that Is(target) returns true.
+func Is(err, target error) bool { return stderrors.Is(err, target) }
+
+// As finds the first error in err's chain that matches target, and if so, sets
+// target to that error value and returns true.
+//
+// The chain consists of err itself followed by the sequence of errors obtained by
+// repeatedly calling Unwrap.
+//
+// An error matches target if the error's concrete value is assignable to the value
+// pointed to by target, or if the error has a method As(interface{}) bool such that
+// As(target) returns true. In the latter case, the As method is responsible for
+// setting target.
+//
+// As will panic if target is not a non-nil pointer to either a type that implements
+// error, or to any interface type. As returns false if err is nil.
+func As(err error, target interface{}) bool { return stderrors.As(err, target) }
+
+// Unwrap returns the result of calling the Unwrap method on err, if err's
+// type contains an Unwrap method returning error.
+// Otherwise, Unwrap returns nil.
+func Unwrap(err error) error {
+	return stderrors.Unwrap(err)
+}