Address error if errata is already present

[moio]

Problem description

This patch prevents the following error:

INFO: Creating errata for CEBA-2019:1331 (CentOS accountsservice BugFix Update) (5 of 22)
Fault returned from XML RPC Server, fault code 2601: redstone.xmlrpc.XmlRpcFault: Errata already exists with advisory CEBA-2019:1331

This happens in case errataImport.pl is trying to add an errata where a published errata that is not linked to any channel already exists.

This can happen, for example, after a channel is deleted - published errata that was only in that channel are not cleaned up.

Such published errata can be found via this one-liner:

spacewalk-sql --select-mode - <<<"SELECT advisory_name FROM rhnErrata e WHERE id NOT IN (SELECT errata_id FROM rhnChannelErrata)"

Solution details

As there is currently no API to get a full list of errata including those not in channels, this patch makes errataImport.pl fail gracefully at errata creation time when the errata already exists by catching the exception and ignoring it selectively.

I am no Perl expert, but my understanding is that the previous code did not really work as intended, as following the condition was always met:

if (defined($result->{faultCode})) {

In case of fault, Frontier would in fact die prior this condition was hit and not return a $result hash at all. So here I am using eval to catch the exceptional case.

HTH!

Fixes #20

[moio]

CC @dvosburg this addresses the error 500 you also saw, it's the same reported as #20

[moio]

@stevemeier this is best reviewed by ignoring whitespace changes 😅