Relax extent hook tests to work with unsplittable extents.
Relax extent hook tests to work with unsplittable extents.

glandium/jemalloc,glandium/jemalloc,8l/jemalloc,8l/jemalloc,8l/jemalloc,wqfish/jemalloc,wqfish/jemalloc,glandium/jemalloc,wqfish/jemalloc,wqfish/jemalloc,glandium/jemalloc,wqfish/jemalloc,8l/jemalloc