Always allow the clean-up to succeed

Signed-off-by: Derek Straka <derek@asterius.io>
(cherry picked from commit 34941a25e9)

scripts/cleanup-env.sh

@@ -1,4 +1,4 @@
-#!/bin/bash -e
+#!/bin/bash -x
 
 # Only attempt to unmount if the directory is already mounted
 if mountpoint -q `pwd`/build; then