Check uid instead of username. (#513)
Check uid instead of username. (#513)

Root may not be root in some cases.

GoogleCloudPlatform/compute-daisy,zmarano/compute-image-tools,zmarano/compute-image-tools,GoogleCloudPlatform/compute-image-tools,adjackura/compute-image-tools,GoogleCloudPlatform/compute-image-import,adjackura/compute-image-tools,GoogleCloudPlatform/compute-daisy,GoogleCloudPlatform/compute-image-import,adjackura/compute-image-tools,GoogleCloudPlatform/compute-image-import,GoogleCloudPlatform/compute-image-tools,GoogleCloudPlatform/compute-image-tools,zmarano/compute-image-tools