[Magma] Coredump seen during rebalance in out with hard failover

./testrunner -i /tmp/ankush.ini  -t rebalance_new.rebalance_in_out.RebalanceInOutTests.test_rebalance_in_out_with_failover,nodes_in=3,nodes_init=3,nodes_out=2,replicas=1,num_items=1000000,rerun=False,magma_storage=True,bucket_storage=magma,infra_log_level=debug,log_level=debug

1  Had a cluster with three nodes

2 Added three nodes 

3 Did hard failover, failed over 1 node 

4. Removed one node

5. Triggered Rebalance 

(gdb) bt

#0  0x00007f20042b1cbd in cache_bin_dalloc_easy (ptr=<optimized out>, bin_info=<optimized out>, bin=<optimized out>)

    at include/jemalloc/internal/cache_bin.h:126

#1  tcache_dalloc_small (slow_path=<optimized out>, binind=<optimized out>, ptr=<optimized out>, tcache=<optimized out>,

    tsd=<optimized out>) at include/jemalloc/internal/tcache_inlines.h:178

#2  arena_dalloc (slow_path=<optimized out>, alloc_ctx=<optimized out>, tcache=<optimized out>, ptr=<optimized out>,

    tsdn=<optimized out>) at include/jemalloc/internal/arena_inlines_b.h:320

#3  idalloctm (slow_path=<optimized out>, is_internal=<optimized out>, alloc_ctx=<optimized out>, tcache=<optimized out>,

    ptr=<optimized out>, tsdn=<optimized out>) at include/jemalloc/internal/jemalloc_internal_inlines_c.h:118

#4  ifree (slow_path=<optimized out>, tcache=<optimized out>, ptr=<optimized out>, tsd=<optimized out>) at src/jemalloc.c:2589

#5  je_dallocx (ptr=ptr@entry=0x7f1fcee09000, flags=<optimized out>) at src/jemalloc.c:3526

#6  0x00007f2004db134f in cb::_JEArenaMalloc<cb::JEArenaCoreLocalTracker>::free (ptr=ptr@entry=0x7f1fcee09000)

    at /home/couchbase/jenkins/workspace/couchbase-server-unix/platform/src/je_arena_malloc.cc:264

#7  0x000000000051677a in free (ptr=0x7f1fcee09000)

    at /home/couchbase/jenkins/workspace/couchbase-server-unix/platform/include/platform/cb_arena_malloc.h:163

#8  cb_free (ptr=ptr@entry=0x7f1fcee09000)

    at /home/couchbase/jenkins/workspace/couchbase-server-unix/platform/src/cb_malloc_arena.cc:75

#9  0x00007f2006c25635 in operator delete (ptr=ptr@entry=0x7f1fcee09000)

    at /home/couchbase/jenkins/workspace/couchbase-server-unix/platform/src/global_new_replacement.cc:84

#10 0x00007f2002b99192 in (anonymous namespace)::run (p=<optimized out>)

    at /tmp/deploy/gcc-7.3.0/libstdc++-v3/libsupc++/atexit_thread.cc:82

#11 0x00007f20023debc2 in __nptl_deallocate_tsd () from /usr/lib64/libpthread-2.17.so

#12 0x00007f20023dedd3 in start_thread () from /usr/lib64/libpthread-2.17.so

#13 0x00007f200210c21d in clone () from /usr/lib64/libc-2.17.so