gwpy.io: return unique creds from parse_keytab
This PR fixes an issue in gwpy.io.kerberos
whereby keytab files with multiple copies of the same kvno/principal would be returned, causing kinit()
to fall over. parse_keytab()
has been modified to return an ordered, unique list of credentials, and also to return a list
of tuple
, rather than a list
of list
.
cc @scottcoughlin2014