compute/metadata: short description of bug

[Deiz]

Client

metadata

Code

e.g.

package main

func main() {
	email, err := metadata.Get("/instance/service-accounts/default/email")
	if err != nil {
		// err should be non-nil if the metadata server is unreachable (i.e. not running on GCP)
	}

	// instead, we wind up here with a zero-value email
}

Expected behavior

When not running on GCP, or otherwise unable to reach the metadata server, this package's operations should fail.

Actual behavior

A nil error and zero-value string are returned.

This is occurring due to the fix for #4713.

[codyoss]

@Deiz Thanks for the report, I will take a look at your PR shortly!