Use sha256 hashes when caching files (#1424)
Use sha256 hashes when caching files (#1424)

Hex encoding can result in filenames that are too long.
quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt,quiltdata/quilt