Increase test coverage in test_decay_ticks.
Increase test coverage in test_decay_ticks.

glandium/jemalloc,AndroidExternal/jemalloc,cpeterso/jemalloc,glandium/jemalloc,leebaok/jemalloc-4.2.1-readcode,jemalloc/jemalloc-cmake,8l/jemalloc,cpeterso/jemalloc,wqfish/jemalloc,glandium/jemalloc,AndroidExternal/jemalloc,jemalloc/jemalloc-cmake,wqfish/jemalloc,wqfish/jemalloc,leebaok/jemalloc-4.2.1-readcode,8l/jemalloc,jemalloc/jemalloc-cmake,8l/jemalloc,wqfish/jemalloc,leebaok/jemalloc-4.2.1-readcode,leebaok/jemalloc-4.2.1-readcode,cpeterso/jemalloc,AndroidExternal/jemalloc,8l/jemalloc,AndroidExternal/jemalloc,glandium/jemalloc,cpeterso/jemalloc,wqfish/jemalloc,jemalloc/jemalloc-cmake