Inconsistency of Scanner when write during scan operation

[eincs]

When modifying same row during intra scanning, in some cases, following exception can be occurred.

java.util.ConcurrentModificationException
    at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1115)
    at java.util.TreeMap$KeyIterator.next(TreeMap.java:1169)
    at com.google.common.collect.Iterators$6.next(Iterators.java:641)
    at kr.co.vcnc.haeinsa.HaeinsaMutation$MutationScanner.peek(HaeinsaMutation.java:152)
    at kr.co.vcnc.haeinsa.HaeinsaTable$ClientScanner.nextScanner(HaeinsaTable.java:1148)
    at kr.co.vcnc.haeinsa.HaeinsaTable$ClientScanner.next(HaeinsaTable.java:1111)
    at kr.co.vcnc.haeinsa.HaeinsaTable$ClientScanner$1.hasNext(HaeinsaTable.java:974)
    ....

This is can be cause inconsistency because it doesn't provide snapshot of hbase when starting scan. Inter-row scanning could have same issue.