vendor: github.com/moby/buildkit v0.8.3-3-g244e8cde

full diff: https://github.com/moby/buildkit/compare/v0.8.3...v0.8.3-3-g244e8cde

- Transform relative mountpoints for exec mounts in the executor
- Add test for handling relative mountpoints

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 61b04b3a02f509dc8580ec3d7824df57336ff3e3)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
diff --git a/vendor.conf b/vendor.conf
index 3fae563..b8cb3ae 100644
--- a/vendor.conf
+++ b/vendor.conf
@@ -33,7 +33,7 @@
 golang.org/x/sync                                   cd5d95a43a6e21273425c7ae415d3df9ea832eeb
 
 # buildkit
-github.com/moby/buildkit                            81c2cbd8a418918d62b71e347a00034189eea455 # v0.8.3
+github.com/moby/buildkit                            244e8cde639f71a05a1a2e0670bd88e0206ce55c # v0.8.3-3-g244e8cde
 github.com/tonistiigi/fsutil                        0834f99b7b85462efb69b4f571a4fa3ca7da5ac9
 github.com/tonistiigi/units                         6950e57a87eaf136bbe44ef2ec8e75b9e3569de2
 github.com/grpc-ecosystem/grpc-opentracing          8e809c8a86450a29b90dcc9efbf062d0fe6d9746
diff --git a/vendor/github.com/moby/buildkit/frontend/gateway/container.go b/vendor/github.com/moby/buildkit/frontend/gateway/container.go
index e124566..f234401 100644
--- a/vendor/github.com/moby/buildkit/frontend/gateway/container.go
+++ b/vendor/github.com/moby/buildkit/frontend/gateway/container.go
@@ -3,6 +3,7 @@
 import (
 	"context"
 	"fmt"
+	"path/filepath"
 	"runtime"
 	"sort"
 	"strings"
@@ -75,7 +76,7 @@
 
 	name := fmt.Sprintf("container %s", req.ContainerID)
 	mm := mounts.NewMountManager(name, w.CacheManager(), sm, w.MetadataStore())
-	p, err := PrepareMounts(ctx, mm, w.CacheManager(), g, mnts, refs, func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {
+	p, err := PrepareMounts(ctx, mm, w.CacheManager(), g, "", mnts, refs, func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {
 		cm := w.CacheManager()
 		if m.Input != opspb.Empty {
 			cm = refs[m.Input].Worker.CacheManager()
@@ -132,7 +133,7 @@
 
 type MakeMutable func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error)
 
-func PrepareMounts(ctx context.Context, mm *mounts.MountManager, cm cache.Manager, g session.Group, mnts []*opspb.Mount, refs []*worker.WorkerRef, makeMutable MakeMutable) (p PreparedMounts, err error) {
+func PrepareMounts(ctx context.Context, mm *mounts.MountManager, cm cache.Manager, g session.Group, cwd string, mnts []*opspb.Mount, refs []*worker.WorkerRef, makeMutable MakeMutable) (p PreparedMounts, err error) {
 	// loop over all mounts, fill in mounts, root and outputs
 	for i, m := range mnts {
 		var (
@@ -254,7 +255,11 @@
 			p.Root = mountWithSession(root, g)
 		} else {
 			mws := mountWithSession(mountable, g)
-			mws.Dest = m.Dest
+			dest := m.Dest
+			if !filepath.IsAbs(filepath.Clean(dest)) {
+				dest = filepath.Join("/", cwd, dest)
+			}
+			mws.Dest = dest
 			mws.Readonly = m.Readonly
 			mws.Selector = m.Selector
 			p.Mounts = append(p.Mounts, mws)
diff --git a/vendor/github.com/moby/buildkit/solver/llbsolver/ops/exec.go b/vendor/github.com/moby/buildkit/solver/llbsolver/ops/exec.go
index 37d64ed..bbf3d17 100644
--- a/vendor/github.com/moby/buildkit/solver/llbsolver/ops/exec.go
+++ b/vendor/github.com/moby/buildkit/solver/llbsolver/ops/exec.go
@@ -240,7 +240,7 @@
 		}
 	}
 
-	p, err := gateway.PrepareMounts(ctx, e.mm, e.cm, g, e.op.Mounts, refs, func(m *pb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {
+	p, err := gateway.PrepareMounts(ctx, e.mm, e.cm, g, e.op.Meta.Cwd, e.op.Mounts, refs, func(m *pb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {
 		desc := fmt.Sprintf("mount %s from exec %s", m.Dest, strings.Join(e.op.Meta.Args, " "))
 		return e.cm.New(ctx, ref, g, cache.WithDescription(desc))
 	})