fix 0 log index (#385)

Signed-off-by: Bob Callaway <bob.callaway@gmail.com>

cmd/rekor-cli/app/pflags.go

@@ -195,7 +195,7 @@ func validateLogIndex(v string) error {
 		return err
 	}
 	l := struct {
-		Index int `validate:"required,gte=0"`
+		Index int `validate:"gte=0"`
 	}{i}
 
 	return useValidator(logIndexFlag, l)

tests/e2e_test.go

@@ -192,6 +192,9 @@ func TestGet(t *testing.T) {
 
 	uuid := getUUIDFromUploadOutput(t, out)
 
+	// since we at least have 1 valid entry, check the log at index 0
+	runCli(t, "get", "--log-index", "0")
+
 	out = runCli(t, "get", "--format=json", "--uuid", uuid)
 
 	// The output here should be in JSON with this structure: