internal/pkg: implementation revisions

This enables changing the behaviour of an artifact implementation without changing its IR structure. Unfortunately this changes the IR header structure resulting in many rebuilds.

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

internal/pkg/file_test.go

@@ -17,7 +17,7 @@ func TestFile(t *testing.T) {
 			cureMany(t, c, []cureStep{
 				{"short", pkg.NewFile("null", []byte{0}), base.Append(
 					"identifier",
-					"3376ALA7hIUm2LbzH2fDvRezgzod1eTK_G6XjyOgbM2u-6swvkFaF0BOwSl_juBi",
+					"J3quqJoHNQID_k-amRdanjl0nXynlU7wzVJUx25BNvL229wxPyQ9s2Td9VbnRP6s",
 				), want, pkg.WNew, nil},
 			})
 		}, expectsFS{
@@ -27,7 +27,7 @@ func TestFile(t *testing.T) {
 			"checksum/" + pkg.Encode(want.hash()): {Mode: 0400, Data: []byte{0}},
 
 			"identifier": {Mode: fs.ModeDir | 0700},
-			"identifier/3376ALA7hIUm2LbzH2fDvRezgzod1eTK_G6XjyOgbM2u-6swvkFaF0BOwSl_juBi": {Mode: fs.ModeSymlink | 0777, Data: []byte("../checksum/vsAhtPNo4waRNOASwrQwcIPTqb3SBuJOXw2G4T1mNmVZM-wrQTRllmgXqcIIoRcX")},
+			"identifier/J3quqJoHNQID_k-amRdanjl0nXynlU7wzVJUx25BNvL229wxPyQ9s2Td9VbnRP6s": {Mode: fs.ModeSymlink | 0777, Data: []byte("../checksum/vsAhtPNo4waRNOASwrQwcIPTqb3SBuJOXw2G4T1mNmVZM-wrQTRllmgXqcIIoRcX")},
 
 			"substitute": {Mode: fs.ModeDir | 0700},