cmd/cue/cmd: fix windows test breakage
cmd/cue/cmd: fix windows test breakage

Change-Id: Ic338fcdb5b06fd95f9d57e17b5fe04bd13989dcc
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/6144
Reviewed-by: CUE cueckoo <0f32a827c9a5f00281f936ac78b5ef3ba80a954c@gmail.com>
Reviewed-by: Paul Jolly <a027184a55211cd23e3f3094f1fdc728df5e0500@myitcv.org.uk>

cuelang/cue