This is to track the regression introduced in master, which needs fixing for 0.14. See #9240, #9371, etc.
{
    for (set<int>::iterator it = setFilesToPrune.begin(); it != setFilesToPrune.end(); ++it) {
        CDiskBlockPos pos(*it, 0);
        boost::filesystem::remove(GetBlockPosFilename(pos, "blk"));
        boost::filesystem::remove(GetBlockPosFilename(pos, "rev"));
        LogPrintf("Prune: %s deleted blk/rev (%05u)\n", __func__, *it);
    }
}
void FindFilesToPruneManual(std::set<int>& setFilesToPrune, int nManualPruneHeight)
{
    assert(fPruneMode && nManualPruneHeight > 0);
    LOCK2(cs_main, cs_LastBlockFile);
    if (chainActive.Tip() == NULL)
        return;
    
    unsigned int nLastBlockWeCanPrune = min((unsigned)nManualPruneHeight, chainActive.Tip()->nHeight - MIN_BLOCKS_TO_KEEP);
    int count=0;
    for (int fileNumber = 0; fileNumber < nLastBlockFile; fileNumber++) {
        if (vinfoBlockFile[fileNumber].nSize == 0 || vinfoBlockFile[fileNumber].nHeightLast > nLastBlockWeCanPrune)
            continue;
        PruneOneBlockFile(fileNumber);
        setFilesToPrune.insert(fileNumber);
        count++;
    }
    LogPrintf("Prune (Manual): prune_height=%d removed %d blk/rev pairs\n", nLastBlockWeCanPrune, count);
}
void PruneBlockFilesManual(int nManualPruneHeight)