Assert fails in lots of tests in the nightly testing.

# Internal Error (/opt/jprt/T/P1/131533.brutisso/s/hotspot/src/share/vm/gc_implementation/g1/heapRegionManager.inline.hpp:43), pid=5600, tid=4091272048
# assert(is_available(index)) failed: pre-condition

Stack trace:

Current thread (0xeb1e3c00): VMThread [stack: 0xf3d3d000,0xf3dbe000] [id=5619]

Stack: [0xf3d3d000,0xf3dbe000], sp=0xf3dbcbd0, free space=510k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xa8ef98] VMError::report_and_die()+0x198;; VMError::report_and_die()+0x198
V [libjvm.so+0x3c9506] report_vm_error(char const*, int, char const*, char const*)+0x76;; report_vm_error(char const*, int, char const*, char const*)+0x76
V [libjvm.so+0x445f7c] G1CollectedHeap::check_cset_fast_test()+0x1ec;; G1CollectedHeap::check_cset_fast_test()+0x1ec
V [libjvm.so+0x453f9d] G1CollectedHeap::do_collection_pause_at_safepoint(double)+0x63d;; G1CollectedHeap::do_collection_pause_at_safepoint(double)+0x63d
V [libjvm.so+0xabac80] VM_G1IncCollectionPause::doit()+0xc0;; VM_G1IncCollectionPause::doit()+0xc0
V [libjvm.so+0xab8ed7] VM_Operation::evaluate()+0x97;; VM_Operation::evaluate()+0x97
V [libjvm.so+0xab6395] VMThread::evaluate_operation(VM_Operation*)+0x145;; VMThread::evaluate_operation(VM_Operation*)+0x145
V [libjvm.so+0xab6ce5] VMThread::loop()+0x4e5;; VMThread::loop()+0x4e5
V [libjvm.so+0xab6f83] VMThread::run()+0x123;; VMThread::run()+0x123
V [libjvm.so+0x8a4090] java_start(Thread*)+0x100;; java_start(Thread*)+0x100
C [libpthread.so.0+0x6a49]

VM_Operation (0xead7d334): G1IncCollectionPause, mode: safepoint, requested by thread 0xeaee2400