Don't ignore containerfiles outside of build context

[NO NEW TESTS NEEDED]

Signed-off-by: Aleksei Kosyrev <albnnc@gmail.com>

pkg/bindings/images/build.go

@@ -695,6 +695,9 @@ func nTar(excludes []string, sources ...string) (io.ReadCloser, error) {
 					}
 					name = filepath.ToSlash(path)
 				}
+				// If name is absolute path, then it has to be containerfile outside of build context.
+				// If not, we should check it for being excluded via pattern matcher.
+				if !filepath.IsAbs(name) {
 					excluded, err := pm.Matches(name) //nolint:staticcheck
 					if err != nil {
 						return fmt.Errorf("checking if %q is excluded: %w", name, err)
@@ -705,6 +708,7 @@ func nTar(excludes []string, sources ...string) (io.ReadCloser, error) {
 						// are required to visit all files. :(
 						return nil
 					}
+				}
 				switch {
 				case dentry.Type().IsRegular(): // add file item
 					info, err := dentry.Info()