Assertion failed with document delete

[Federico Cavalieri]

The following query causes an assertion failure.
import module namespace doc = "http://www.zorba-xquery.com/modules/store/dynamic/documents";

doc:put("foo", document { <foo>bar</foo> });

(
doc:remove("foo"),
doc:remove("foo")
);

[Federico Cavalieri (fcavalieri)]

<?xml version="1.0" encoding="UTF-8"?>
Zorba API error [zerr:ZAPI0020]: "file:///zorba/test/foo": document already exists in store; raised at /zorba/repository/pulprocessing/src/store/naive/simple_store.cpp:1125
battlezone@M1710-linux:/zorba/build/pulprocessing$ bin/zorba -f -q /zorba/test/test13.xq
<?xml version="1.0" encoding="UTF-8"?>
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(+0xeda63b) [0x1d3b63b]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba16assertion_failedEPKcS1_i+0x22) [0x1d3b6fe]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba11simplestore17UpdDeleteDocument5applyEv+0xbf) [0x255e151]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba11simplestore9applyListERSt6vectorIPNS0_15UpdatePrimitiveESaIS3_EE+0x57) [0x2542030]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba11simplestore7PULImpl12applyUpdatesEb+0xf3) [0x2546f55]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba13apply_updatesEPNS_10CompilerCBEPNS_15dynamic_contextEPNS_14static_contextEPNS_5store3PULERKNS_8QueryLocE+0x371) [0x221f574]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZNK5zorba13ApplyIterator8nextImplERNS_5store10ItemHandleINS1_4ItemEEERNS_9PlanStateE+0x1d5) [0x221f075]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZNK5zorba7BatcherINS_13ApplyIteratorEE11produceNextERNS_5store10ItemHandleINS3_4ItemEEERNS_9PlanStateE+0x9f) [0x22233f9]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba12PlanIterator11consumeNextERNS_5store10ItemHandleINS1_4ItemEEEPKS0_RNS_9PlanStateE+0x79) [0x2206b77]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZNK5zorba18SequentialIterator8nextImplERNS_5store10ItemHandleINS1_4ItemEEERNS_9PlanStateE+0xec) [0x23c3982]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZNK5zorba7BatcherINS_18SequentialIteratorEE11produceNextERNS_5store10ItemHandleINS3_4ItemEEERNS_9PlanStateE+0x9f) [0x23d2b69]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba12PlanIterator11consumeNextERNS_5store10ItemHandleINS1_4ItemEEEPKS0_RNS_9PlanStateE+0x79) [0x2206b77]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba11PlanWrapper4nextERNS_5store10ItemHandleINS1_4ItemEEE+0xa0) [0x220655e]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba10serializer9serializeENS_8rchandleINS_5store8IteratorEEERSoPNS_19SAX2_ContentHandlerE+0x295) [0x19e684f]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba10serializer9serializeENS_8rchandleINS_5store8IteratorEEERSo+0x46) [0x19e6590]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba10XQueryImpl9serializeERSoRNS_8rchandleINS_11PlanWrapperEEEPK23Zorba_SerializerOptions+0x9c) [0x198bce0]
/zorba/build/pulprocessing/src/libzorba_simplestore.so.2.0.1(_ZN5zorba10XQueryImpl7executeERSoPK23Zorba_SerializerOptions+0xcd) [0x198b0eb]
bin/zorba(_Z17compileAndExecutePN5zorba5ZorbaERK18ZorbaCMDPropertiesRNS_8SmartPtrINS_13StaticContextEEERKSsRSiRSoR10TimingInfo+0x4e4) [0x805a3e2]
bin/zorba(main+0xd41) [0x805b6cc]
/lib/i386-linux-gnu/libc.so.6(__libc_star...