go: Replace Logrus with go-logging.

go/src/infra/libs/auth/auth.go

Index: go/src/infra/libs/auth/auth.go
diff --git a/go/src/infra/libs/auth/auth.go b/go/src/infra/libs/auth/auth.go
index 344abc75cb17e63d5ee2c77180187b5672899f1e..fcfdecb19bd3a10265705b27845f7863c86fe9a9 100644
--- a/go/src/infra/libs/auth/auth.go
+++ b/go/src/infra/libs/auth/auth.go
@@ -52,10 +52,6 @@ var (
 	// can't be minted for given OAuth scopes. For example if GCE instance wasn't
 	// granted access to requested scopes when it was created.
 	ErrInsufficientAccess = internal.ErrInsufficientAccess
-
-	// ErrNoTerminal is returned by Login() if interaction with a user is
-	// required, but the process is not attached to a terminal.
-	ErrNoTerminal = errors.New("Can't interact with a user: no terminal")
 )
 
 // Known Google API OAuth scopes.
@@ -322,11 +318,6 @@ func (a *authenticatorImpl) Login() error {
 		return nil
 	}
 
-	// Active terminal is required for interaction with a user.
-	if !logging.IsTerminal {
-		return ErrNoTerminal
-	}
-
 	// Create initial token. This may require interaction with a user.
 	a.token, err = a.provider.MintToken()
 	if err != nil {