vendor: update buildkit to master@8b7bcb900d3c

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/containerd/containerd/content/helpers.go

@@ -21,12 +21,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"math/rand"
 	"sync"
 	"time"
 
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/opencontainers/go-digest"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
@@ -59,6 +59,10 @@ func NewReader(ra ReaderAt) io.Reader {
 //
 // Avoid using this for large blobs, such as layers.
 func ReadBlob(ctx context.Context, provider Provider, desc ocispec.Descriptor) ([]byte, error) {
+	if int64(len(desc.Data)) == desc.Size && digest.FromBytes(desc.Data) == desc.Digest {
+		return desc.Data, nil
+	}
+
 	ra, err := provider.ReaderAt(ctx, desc)
 	if err != nil {
 		return nil, err
@@ -119,7 +123,7 @@ func OpenWriter(ctx context.Context, cs Ingester, opts ...WriterOpt) (Writer, er
 			// error or abort. Requires asserting for an ingest manager
 
 			select {
-			case <-time.After(time.Millisecond * time.Duration(rand.Intn(retry))):
+			case <-time.After(time.Millisecond * time.Duration(randutil.Intn(retry))):
 				if retry < 2048 {
 					retry = retry << 1
 				}

vendor/github.com/containerd/containerd/content/local/store.go

@@ -20,7 +20,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -32,6 +31,7 @@ import (
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/filters"
 	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/pkg/randutil"
 	"github.com/sirupsen/logrus"
 
 	"github.com/opencontainers/go-digest"
@@ -473,7 +473,7 @@ func (s *store) Writer(ctx context.Context, opts ...content.WriterOpt) (content.
 			lockErr = nil
 			break
 		}
-		time.Sleep(time.Millisecond * time.Duration(rand.Intn(1<<count)))
+		time.Sleep(time.Millisecond * time.Duration(randutil.Intn(1<<count)))
 	}
 
 	if lockErr != nil {