Remove PackageEntry._clone (#1449)
Remove PackageEntry._clone (#1449)

Cloning (especially using deepcopy) is very expensive. Copy only the parts we care about.
quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt,quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt-compiler