internal/pkg: expose cure whence

Useful for cure determinism validation of KindExec.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/compress_test.go

@@ -43,7 +43,7 @@ func TestDecompress(t *testing.T) {
 					&client,
 					"file:///testdata",
 					pkg.Checksum{0xfd},
-				), pkg.Gzip), nil, nil, &pkg.ChecksumMismatchError{
+				), pkg.Gzip), nil, nil, pkg.WNew, &pkg.ChecksumMismatchError{
 					Got:  testdataChecksum,
 					Want: pkg.Checksum{0xfd},
 				}},
@@ -52,7 +52,7 @@ func TestDecompress(t *testing.T) {
 					&client,
 					"file:///testdata",
 					testdataChecksum,
-				), pkg.Gzip), ignorePathname, expectsChecksum(sha512.Sum384([]byte{0})), nil},
+				), pkg.Gzip), ignorePathname, expectsChecksum(sha512.Sum384([]byte{0})), pkg.WNew, nil},
 			})
 		}, expectsFS{
 			".": {Mode: fs.ModeDir | 0700},