memcached crash on 7.6.0-2180 (MP1): violating invariant "getItemsForCursor: Limits must be > 0"

Steps:

1. Initialise a 1 node KV cluster
2. The cluster is configured with just 2 vbuckets.
3. Create a Magma bucket with 250GB memory and start loading data
4. Data load consists of doc sizes which are in the range of (2MB - 18MB).
5. Loaded about 13,000 docs.
6. Rebalanced-in a node and observed the following during rebalance
   Since the bucket only has 2vbuckets, during rebalance-in, only 1 vbucket was moving from the source to the destination node.

7. Rebalance exited with reason {mover_crashed,

   {unexpected_exit,

   {'EXIT',<0.20525.1>,

   {{{{badmatch,{error,timeout}},

   [{mc_client_binary,stats_recv,4,

   [{file,"src/mc_client_binary.erl"},

   {line,172}]},

   {mc_client_binary,stats,4,

   [{file,"src/mc_client_binary.erl"},

   {line,499}]},

   {ns_memcached,do_handle_call,3,

   [{file,"src/ns_memcached.erl"},

   {line,620}]},

   {ns_memcached,worker_loop,3,

   [{file,"src/ns_memcached.erl"},

   {line,243}]},

   {proc_lib,init_p_do_apply,3,

   [{file,"proc_lib.erl"},{line,240}]}]},

   {gen_server,call,

   ['ns_memcached-test_bucket',

   {get_dcp_docs_estimate,1,

   "replication:ns_1@172.31.30.47->ns_1@ec2-54-88-120-100.compute-1.amazonaws.com:test_bucket"},

   300000]}},

   {gen_server,call,

   [{'janitor_agent-test_bucket',

   'ns_1@172.31.30.47'},

   {if_rebalance,<0.20500.1>,

   {wait_dcp_data_move,

   ['ns_1@ec2-54-88-120-100.compute-1.amazonaws.com'],

   1}},

   infinity]}}}}}.

   Rebalance Operation Id = 472f8c4c222090b8a956b2c3217f2438

1. Stack backtrace of crashed thread:

   #0  /opt/couchbase/bin/memcached() [0x400000+0x835001]

   #1  /opt/couchbase/bin/memcached(_ZN15google_breakpad16ExceptionHandler12GenerateDumpEPNS0_12CrashContextE+0x385) [0x400000+0x852ec5]

   #2  /opt/couchbase/bin/memcached(_ZN15google_breakpad16ExceptionHandler13SignalHandlerEiP9siginfo_tPv+0x9f) [0x400000+0x85320f]

   #3  /lib64/libc.so.6() [0x7f7a77a00000+0x54df0]

   #4  /lib64/libc.so.6() [0x7f7a77a00000+0xa154c]

   #5  /lib64/libc.so.6(raise+0x16) [0x7f7a77a00000+0x54d46]

   #6  /lib64/libc.so.6(abort+0xd3) [0x7f7a77a00000+0x287f3]

   #7  /opt/couchbase/bin/../lib/libstdc++.so.6() [0x7f7a77e00000+0xa89ab]

   #8  /opt/couchbase/bin/memcached() [0x400000+0x844fe6]

   #9  /opt/couchbase/bin/../lib/libstdc++.so.6() [0x7f7a77e00000+0xb82fa]

   #10 /opt/couchbase/bin/../lib/libstdc++.so.6() [0x7f7a77e00000+0xb8365]

   #11 /opt/couchbase/bin/../lib/libstdc++.so.6() [0x7f7a77e00000+0xb85b7]

   #12 /opt/couchbase/bin/memcached() [0x400000+0x92c015]

   #13 /opt/couchbase/bin/memcached() [0x400000+0xbf5f4]

   #14 /opt/couchbase/bin/memcached() [0x400000+0x47e318]

   #15 /opt/couchbase/bin/memcached() [0x400000+0x5ab271]

   #16 /opt/couchbase/bin/memcached() [0x400000+0x5b37e3]

   #17 /opt/couchbase/bin/memcached() [0x400000+0x5b3949]

   #18 /opt/couchbase/bin/memcached() [0x400000+0x5b9bb1]

   #19 /opt/couchbase/bin/memcached() [0x400000+0x78c76f]

   #20 /opt/couchbase/bin/memcached() [0x400000+0x4f77f2]

   #21 /opt/couchbase/bin/memcached() [0x400000+0x78a50a]

   #22 /opt/couchbase/bin/memcached() [0x400000+0x78d8c3]

   #23 /opt/couchbase/bin/memcached() [0x400000+0x92800f]

   #24 /opt/couchbase/bin/memcached() [0x400000+0x910b37]

   #25 /opt/couchbase/bin/memcached() [0x400000+0x92abaa]

   #26 /opt/couchbase/bin/memcached() [0x400000+0x786850]

   #27 /opt/couchbase/bin/../lib/libstdc++.so.6() [0x7f7a77e00000+0xe4aa3]

   #28 /lib64/libc.so.6() [0x7f7a77a00000+0x9f802]

   #29 /lib64/libc.so.6() [0x7f7a77a00000+0x3f450]

1. Cb-collect logs are attached.