Work around problem where 'del os.environ["FOO"]' doesn't update environment. test-hook failed since changeset 949516072388 because of this on Solaris 8.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m test -d "1000000 0"
hg history
hg manifest --debug
hg cat a
hg verify