muteHttpExceptions = true throws authentication failure - google-apps-script

Question

Using the Google Apps Email Settings API a delegate is deleted with the script below. If an error occurs, for example trying to delete delegates that do not exist, the following message is returned:
Exception: Request failed for returned code 400. Truncated server
response: <xml version="1.0" encoding="UTF-8"?>
<AppsForYourDomainErrors> <error errorCode="1303"
invalidInput="XXXX#XXXX.com" reason="E... (use muteHttpExceptions
option to examine full response)
However when using muteHttpExceptions = true the authentication fails:
Exception: Failed to authenticate for service: google
This forces me to use a try / catch structure instead of examining the HTTPResponse object. I would like to know why this is happening and how to solve it.
The test function:
function test() {
var consumerKey = 'XXXX';
var consumerSecret = 'XXXX';
var domain = 'XXXX.com';
var userName = 'XXXX'
var delegateName = 'XXXX#XXXX.com'
var serviceName = 'google';
var scope = 'https://apps-apis.google.com/a/feeds/emailsettings/2.0/';
var oAuthConfig = UrlFetchApp.addOAuthService(serviceName);
oAuthConfig.setRequestTokenUrl('https://www.google.com/accounts/OAuthGetRequestToken?scope=' + scope);
oAuthConfig.setAuthorizationUrl('https://www.google.com/accounts/OAuthAuthorizeToken');
oAuthConfig.setAccessTokenUrl('https://www.google.com/accounts/OAuthGetAccessToken');
oAuthConfig.setConsumerKey(consumerKey);
oAuthConfig.setConsumerSecret(consumerSecret);
var fetchParameters = {};
fetchParameters.oAuthServiceName = serviceName;
fetchParameters.oAuthUseToken = 'always';
fetchParameters.method = 'DELETE';
fetchParameters.muteHttpExceptions = false;
try {
var url = 'https://apps-apis.google.com/a/feeds/emailsettings/2.0/'+ domain + '/' + userName + '/delegation/' + delegateName;
var result = UrlFetchApp.fetch(url, fetchParameters);
} catch (e) {
Logger.log(e);
}
}

Answer 1

This question has been posted to the Google Apps Script issue tracker as ticket 3478 and acknowledged as a bug. The ticket remains open but the following workaround has been proposed:
Revoking access in your Google Account's Security settings to both www.google.com AND the source of Apps Script (spreadsheet etc).
Change the oAuthServiceName parameter to something else.
Re-running the script