rhsda.extract_cves_from_input() no longer ignores case when removing duplicates

[ryran]

WHOOPS.

$ pdftotext Openssh_Scan_Report.pdf - | egrep -io 'CVE-[0-9]{4}-[0-9]{4,}'
CVE-2016-3115
CVE-2016-3115
CVE-2016-3115
cve-2016-3115
CVE-2015-5352

$ pdftotext Openssh_Scan_Report.pdf - | egrep -io 'CVE-[0-9]{4}-[0-9]{4,}' | rhsecapi -0 --dryrun
[NOTICE ] rhsda: Found 3 CVEs on stdin; 2 duplicates removed
[NOTICE ] rhsecapi: Skipping CVE retrieval due to --dryrun; would have retrieved: 3

CVE-2016-3115 CVE-2015-5352 CVE-2016-3115