internal/pkg: do not discard the result of compact

This result was mistakenly unused resulting in incorrect identifiers for artifacts with duplicate dependencies.

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

internal/pkg/testdata/main.go

@@ -161,7 +161,7 @@ func main() {
 				log.Fatal("unexpected artifact checksum")
 			}
 		} else {
-			ident = "o4z73RXEjkF5BBoXYg4WZ3c4VCjwvfJtPKFrstFHcEQxkVDoWTtdc5TMXigFvTsF"
+			ident = "tfjrsVuBuFgzWgwz-yPppFtylYuC1VFWnKhyBiHbWTGkyz8lt7Ee9QXWaIHPXs4x"
 
 			lowerdirsEscaped := strings.Split(lowerdir, ":")
 			lowerdirs := lowerdirsEscaped[:0]
@@ -212,7 +212,7 @@ func main() {
 
 	next()
 	if overlayWork {
-		ident = "5ynpgDp5mcAmbFndOESXjQnOy_RG6furIxDpQz6c0bImBBLMAI8FouNbAB0uNs6f"
+		ident = "acaDzHZv40dZaz4cGAXayqbRMgbEOuiuiUijZL8IgDQvyeCNMFE3onBMYfny-kXA"
 		if m.Root != "/" || m.Target != "/work" ||
 			m.Source != "overlay" || m.FsType != "overlay" {
 			log.Fatal("unexpected work mount entry")