chore: clean up file copy logic backend logic

This avoids duplication of the AttemptUnpackDockerCompatability
handling.

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

Author: jedevc

solver/llbsolver/file/backend.go

@@ -215,27 +215,22 @@ func docopy(ctx context.Context, src, dest string, action pb.FileActionCopy, u *
 		copy.WithXAttrErrorHandler(xattrErrorHandler),
 	}
 
+	var m []string
 	if !action.AllowWildcard {
-		if action.AttemptUnpackDockerCompatibility {
-			if ok, err := unpack(ctx, src, srcPath, dest, destPath, ch, timestampToTime(action.Timestamp)); err != nil {
-				return err
-			} else if ok {
-				return nil
-			}
+		m = []string{srcPath}
+	} else {
+		var err error
+		m, err = copy.ResolveWildcards(src, srcPath, action.FollowSymlink)
+		if err != nil {
+			return err
 		}
-		return copy.Copy(ctx, src, srcPath, dest, destPath, opt...)
-	}
-
-	m, err := copy.ResolveWildcards(src, srcPath, action.FollowSymlink)
-	if err != nil {
-		return err
-	}
 
-	if len(m) == 0 {
-		if action.AllowEmptyWildcard {
-			return nil
+		if len(m) == 0 {
+			if action.AllowEmptyWildcard {
+				return nil
+			}
+			return errors.Errorf("%s not found", srcPath)
 		}
-		return errors.Errorf("%s not found", srcPath)
 	}
 
 	for _, s := range m {