Reset REQUEST, GET & POST in main tearDown

Reset REQUEST, GET & POST in main tearDown

I've been noticing tests failing on lines which indicate they were getting variables from these - e.g

CRM_Member_Form_MembershipTest::testSubmitUpdateMembershipFromPartiallyPaid
CiviCRM_API3_Exception: Expected one Contact but found 0

/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/api/api.php:45
/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/CRM/Contribute/Form/AbstractEditPayment.php:757
/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/CRM/Contribute/Form/AbstractEditPayment.php:256
/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/CRM/Member/Form.php:153
/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/CRM/Member/Form/Membership.php:224
/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/tests/phpunit/CRM/Member/Form/MembershipTest.php:832
/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/tests/phpunit/CRM/Member/Form/MembershipTest.php:895
/home/jenkins/bknix-dfl/build/core-13854-7x4fu/sites/all/modules/civicrm/tests/phpunit/CiviTest/CiviUnitTestCase.php:196
/home/jenkins/bknix-dfl/civicrm-buildkit/extern/phpunit5/phpunit5.phar:598