allocator-test: ensure exhaustion includes quarantine

tests/allocator-test.cc

diff --git a/tests/allocator-test.cc b/tests/allocator-test.cc
index 9abbc7e..6444edc 100644
--- a/tests/allocator-test.cc
+++ b/tests/allocator-test.cc
@@ -172,6 +172,13 @@
 			freeStart.notify_one();
 		});
 
+		/*
+		 * Empty the allocator's quarantine so that we're sure that the nullptr
+		 * failure we see below isn't because we aren't allowing the revocation
+		 * state machine to advance.
+		 */
+		heap_quarantine_empty();
+
 		bool memoryExhausted = false;
 		for (auto &allocation : allocations)
 		{