fix(debian): don't include empty licenses for dpkgs (#8623)

Author: DmitriyLewen

pkg/fanal/analyzer/pkg/dpkg/copyright.go

@@ -90,6 +90,10 @@ func (a *dpkgLicenseAnalyzer) parseCopyright(r xio.ReadSeekerAt) ([]types.Licens
 			l = normalizeLicense(l)
 			if l != "" {
 				for _, lic := range licensing.SplitLicenses(l) {
+					if lic == "" {
+						continue
+					}
+
 					lic = licensing.Normalize(lic)
 					if !slices.Contains(licenses, lic) {
 						licenses = append(licenses, lic)
@@ -101,7 +105,7 @@ func (a *dpkgLicenseAnalyzer) parseCopyright(r xio.ReadSeekerAt) ([]types.Licens
 			license := commonLicenseReferenceRegexp.FindStringSubmatch(line)
 			if len(license) == 2 {
 				l := licensing.Normalize(license[1])
-				if !slices.Contains(licenses, l) {
+				if l != "" && !slices.Contains(licenses, l) {
 					licenses = append(licenses, l)
 				}
 			}

pkg/fanal/analyzer/pkg/dpkg/testdata/license-pattern-and-classifier-copyright

@@ -47,7 +47,7 @@ Files: contrib/minizip/*
 Copyright: 1998-2010 Gilles Vollant
            2007-2008 Even Rouault
            2009-2010 Mathias Svensson
-License: Zlib
+License: Zlib,
 
 Files: debian/*
 Copyright: 2000-2017 Mark Brown