fix: skip merging if no dependencies found

Dependency resolving is complicated, bldr might skip even declared
dependencies (if they got promoted to the base image).

This fixes the check to avoid merging if only one layer will be present.

Signed-off-by: Andrey Smirnov <[email protected]>

Author: smira

internal/pkg/convert/node.go

@@ -122,10 +122,6 @@ func (node *NodeLLB) convertDependency(dep solver.PackageDependency) (depState l
 }
 
 func (node *NodeLLB) dependencies(root llb.State) (llb.State, error) {
-	if len(node.Dependencies) == 0 {
-		return root, nil
-	}
-
 	deps := make([]solver.PackageDependency, 0, len(node.Dependencies))
 
 	// collect all the dependencies including transitive runtime dependencies
@@ -176,6 +172,10 @@ func (node *NodeLLB) dependencies(root llb.State) (llb.State, error) {
 		}
 	}
 
+	if len(stages) == 1 {
+		return root, nil
+	}
+
 	return root.WithOutput(llb.Merge(stages, llb.WithCustomName(node.Prefix+"copy")).Output()), nil
 }