Impalad crashes during cancellation on the insert path.

(gdb) bt
#0  0x0000003dc0432635 in raise () from /lib64/libc.so.6
#1  0x0000003dc0433d9d in abort () from /lib64/libc.so.6
#2  0x0000003dc042b75e in __assert_fail_base () from /lib64/libc.so.6
#3  0x0000003dc042b820 in __assert_fail () from /lib64/libc.so.6
#4  0x0000000001f25e3c in impala::FunctionContextImpl::FreeLocalAllocations (this=0x21110c60) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/udf/udf.cc:387
#5  0x0000000000eb10d8 in impala::ExprContext::FreeLocalAllocations (this=0x21178790) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/exprs/expr-context.cc:109
#6  0x0000000000f37bf4 in impala::RuntimeState::FreeLocalExprAllocations (this=0xa9bb100) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/runtime/runtime-state.cc:328
#7  0x0000000000f37864 in impala::RuntimeState::QueryMaintenance (this=0xa9bb100) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/runtime/runtime-state.cc:295
#8  0x0000000001545656 in impala::HdfsScanner::CommitRows (this=0x17b550e0, num_rows=455) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/exec/hdfs-scanner.cc:142
#9  0x000000000147c663 in impala::HdfsAvroScanner::ProcessRange (this=0x17b550e0) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/exec/hdfs-avro-scanner.cc:569
#10 0x0000000001529ec2 in impala::BaseSequenceScanner::ProcessSplit (this=0x17b550e0) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/exec/base-sequence-scanner.cc:140
#11 0x000000000144a327 in impala::HdfsScanNode::ScannerThread (this=0xa353700) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/exec/hdfs-scan-node.cc:838
#12 0x000000000145cd7f in boost::_mfi::mf0<void, impala::HdfsScanNode>::operator() (this=0x7fadb5fb0cd8, p=0xa353700) at /usr/include/boost/bind/mem_fn_template.hpp:49
#13 0x000000000145c4f0 in boost::_bi::list1<boost::_bi::value<impala::HdfsScanNode*> >::operator()<boost::_mfi::mf0<void, impala::HdfsScanNode>, boost::_bi::list0> (this=0x7fadb5fb0ce8, f=..., a=...)
    at /usr/include/boost/bind/bind.hpp:253
#14 0x000000000145b3fb in boost::_bi::bind_t<void, boost::_mfi::mf0<void, impala::HdfsScanNode>, boost::_bi::list1<boost::_bi::value<impala::HdfsScanNode*> > >::operator() (this=0x7fadb5fb0cd8)
    at /usr/include/boost/bind/bind_template.hpp:20
#15 0x0000000001459f9e in boost::detail::function::void_function_obj_invoker0<boost::_bi::bind_t<void, boost::_mfi::mf0<void, impala::HdfsScanNode>, boost::_bi::list1<boost::_bi::value<impala::HdfsScanNode*> > >, void>::invoke (
    function_obj_ptr=...) at /usr/include/boost/function/function_template.hpp:153
#16 0x0000000000f2335d in boost::function0<void>::operator() (this=0x7fadb5fb0cd0) at /usr/include/boost/function/function_template.hpp:1013
#17 0x000000000115d864 in impala::Thread::SuperviseThread (name="scanner-thread(1)", category="hdfs-scan-node", functor=..., thread_started=0x7fadb2e2a550)
    at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/util/thread.cc:311
#18 0x0000000001165c0a in boost::_bi::list4<boost::_bi::value<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::_bi::value<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::_bi::value<boost::function<void()> >, boost::_bi::value<impala::Promise<long int>*> >::operator()<void (*)(const std::string&, const std::string&, impala::Thread::ThreadFunctor, impala::Promise<long int>*), boost::_bi::list0>(boost::_bi::type<void>, void (*&)(const std::string &, const std::string &, impala::Thread::ThreadFunctor, impala::Promise<long> *), boost::_bi::list0 &, int) (this=0xa6d8910, f=@0xa6d8908, a=...) at /usr/include/boost/bind/bind.hpp:457
#19 0x0000000001165b51 in boost::_bi::bind_t<void, void (*)(const std::string&, const std::string&, impala::Thread::ThreadFunctor, impala::Promise<long int>*), boost::_bi::list4<boost::_bi::value<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::_bi::value<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::_bi::value<boost::function<void()> >, boost::_bi::value<impala::Promise<long int>*> > >::operator()(void)
    (this=0xa6d8908) at /usr/include/boost/bind/bind_template.hpp:20
#20 0x0000000001165ade in boost::detail::thread_data<boost::_bi::bind_t<void, void (*)(const std::string&, const std::string&, impala::Thread::ThreadFunctor, impala::Promise<long int>*), boost::_bi::list4<boost::_bi::value<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::_bi::value<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::_bi::value<boost::function<void()> >, boost::_bi::value<impala::Promise<long int>*> > > >::run(void) (this=0xa6d8780) at /usr/include/boost/thread/detail/thread.hpp:61
#21 0x0000000001599c74 in thread_proxy ()
#22 0x0000003dc08079d1 in start_thread () from /lib64/libpthread.so.0
#23 0x0000003dc04e886d in clone () from /lib64/libc.so.6
(gdb) f 4
#4  0x0000000001f25e3c in impala::FunctionContextImpl::FreeLocalAllocations (this=0x21110c60) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/udf/udf.cc:387
387	  assert(!closed_);
(gdb) f 5
#5  0x0000000000eb10d8 in impala::ExprContext::FreeLocalAllocations (this=0x21178790) at /data/2/jenkins/workspace/impala-CI-cdh5-2.0_5.2.0/repos/Impala/be/src/exprs/expr-context.cc:109
109	    fn_contexts_[i]->impl()->FreeLocalAllocations();
(gdb)