go/zodb/fs1tools: test: Normalize dumpOk from py3 to py2 syntax

Because else, py3_pickle3 tests fail e.g. as

        --- FAIL: TestFsDump/py3_pickle3/db=1 (0.00s)
            dump_test.go:70: fsdump: dump different:
                 Trans #00000 tid=0285cbac70a3d733 size=211 time=1979-01-03 21:00:26.400001 offset=117
                -    status='p' user=b'user0.12' description=b'step 0.12'
                +    status='p' user='user0.12' description='step 0.12'

        --- FAIL: TestFsDumpv/py3_pickle3/db=1 (0.00s)
            dump_test.go:70: fsdumpv: dump different:
                 ************************************************************
                -file identifier: b'FS30'
                +file identifier: 'FS30'

        ...

fs1tools/go sticks to py2 syntax because in my view it is more user
friendly. The preference of py2 or py3 syntax needs to be made anyway
because for fs1tools/go it is not possible to know beforehand to which
py kind its output will be compared against.

I think it is not very good for fstools/py output to be dependent on
python version. For the reference on this topic: output of zodbtools/py
is designed to be the same on both py2 and py3.

go/zodb/storage/fs1/fs1tools/dump_test.go

@@ -25,6 +25,7 @@ import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
+	"strings"
 	"testing"
 
 	"lab.nexedi.com/kirr/neo/go/internal/xtesting"
@@ -53,9 +54,6 @@ func testDump(t *testing.T, dir fs1.IterDir, newd func() Dumper) {
 }
 
 func _testDump(t *testing.T, dir fs1.IterDir, newd func() Dumper, z *ZTestData) {
-	if z.Kind == "py3_pickle3" {
-		t.Skip("xfail")
-	}
 	testv := []string{"1", "empty", "whiteout"}
 	for _, tt := range testv {
 		t.Run("db=" + tt, func(t *testing.T) {
@@ -69,6 +67,18 @@ func _testDump(t *testing.T, dir fs1.IterDir, newd func() Dumper, z *ZTestData)
 
 			dumpOk := loadFile(t, z.Path(fmt.Sprintf("/%s.%s.ok", tt, d.DumperName())))
 
+			// normalize dumpOk from py3 to py2 and go outputs:
+			// bytestrings come as '...' on py2 and b'...' on py3
+			if strings.HasPrefix(z.Kind, "py3") {
+				sub := func(old, new string) {
+					dumpOk = strings.ReplaceAll(dumpOk, old, new)
+				}
+				sub(`: b'`, `: '`)
+				sub(`: b"`, `: "`)
+				sub(`=b'`,  `='`)
+				sub(`=b"`,  `="`)
+			}
+
 			if dumpOk != buf.String() {
 				t.Errorf("%s: dump different:\n%v", d.DumperName(), diff.Diff(dumpOk, buf.String()))
 			}