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/exec_test.go

@@ -193,7 +193,7 @@ func TestExec(t *testing.T) {
 			})
 
 			testtoolDestroy(t, base, c)
-		}, pkg.MustDecode("RibudsoY1X4_dtshfvL5LYfCPcxVnP0ikOn3yBHzOrt6BpevQiANLJF6Xua76-gM")},
+		}, pkg.MustDecode("q8x2zQg4YZbKpPqKlEBj_uxXD9vOBaZ852qOuIsl9QdO73I_UMNpuUoPLtunxUYl")},
 
 		{"multiple layers", nil, func(t *testing.T, base *check.Absolute, c *pkg.Cache) {
 			c.SetStrict(true)
@@ -244,7 +244,7 @@ func TestExec(t *testing.T) {
 			})
 
 			testtoolDestroy(t, base, c)
-		}, pkg.MustDecode("a05V6iVGAfLO8aG0VSSFyB1QvnzJoMmGbMX6ud8CMMbatvyBv90_xGn1qWEIsjkQ")},
+		}, pkg.MustDecode("SITnQ6PTV12PAQQjIuLUxkvsXQiC9Gq_HJQlcb4BPL5YnRHnx8lsW7PRM9YMLBsx")},
 	})
 }