[SECURITY-158] Fixing doFillCredentialsIdItems for SubversionTagAction.
Amends 399f17a.
[SECURITY-158] checkCredentialsId/fillCredentialsIdItems cannot be called on a null context.
Amends 399f17a.
Comment.
[SECURITY-158] checkCredentialsId/fillCredentialsIdItems were not actually being used as intended.
Amends 399f17a.