test/framework fix docker pod log collector

When using ExecContainerInput to create the tarball, the same buffer
got used for stdout and stderr. This broke the tarball which resulted
in not extracting the files.

Author: chrischdi

test/framework/docker_logcollector.go

@@ -17,6 +17,7 @@ limitations under the License.
 package framework
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"os"
@@ -106,8 +107,10 @@ func (k DockerLogCollector) collectLogsFromNode(ctx context.Context, outputPath
 
 			defer os.Remove(tempfileName)
 
+			var execErr string
 			execConfig := container.ExecContainerInput{
 				OutputBuffer: f,
+				ErrorBuffer:  bytes.NewBufferString(execErr),
 			}
 			err = containerRuntime.ExecContainer(
 				ctx,
@@ -116,7 +119,7 @@ func (k DockerLogCollector) collectLogsFromNode(ctx context.Context, outputPath
 				"tar", "--hard-dereference", "--dereference", "--directory", containerDir, "--create", "--file", "-", ".",
 			)
 			if err != nil {
-				return err
+				return errors.Wrapf(err, execErr)
 			}
 
 			err = os.MkdirAll(outputDir, os.ModePerm)