It appears that `-prune` is ignored during import (`-reindex`, or `-loadblock`).


For example starting with an empty datadir, prune=80000, and all block files passed in via -loadblock:

```
...
2021-12-23T12:49:44Z [loadblk] [node/blockstorage.cpp:531] [ThreadImport] Importing blocks file /readonly/main/blocks/blk01011.dat...
2021-12-23T12:49:44Z [loadblk] [node/blockstorage.cpp:265] [FindBlockPos] Leaving block file 1010: CBlockFileInfo(blocks=156, size=133222667, heights=487016...487360, time=2017-09-26...2017-09-28)
2021-12-23T12:49:45Z [loadblk] [flatfile.cpp:69] [Allocate] Pre-allocating up to position 0x1000000 in blk01011.dat
2021-12-23T12:49:45Z [loadblk] [logging/timer.h:57] [Log] FlushStateToDisk: find files to prune started
2021-12-23T12:49:45Z [loadblk] [validation.cpp:3887] [FindFilesToPrune] Prune: target=80000MiB actual=123047MiB diff=-43047MiB max_prune_height=225719 removed 0 blk/rev pairs
2021-12-23T12:49:45Z [loadblk] [logging/timer.h:57] [Log] FlushStateToDisk: find files to prune completed (0.05ms)
...
```

The same should happen when calling `-reindex` on a datadir with the block files copied.

So prune only works with IBD from the network?
nRwind++;  start on
            blkdat.StLimit();  rmov 
            unsind int nSiz = 0;
            try {
                 locat a 
                unsind char bu[CMssaHadr::MESSAGE_START_SIZE];
                blkdat.FindByt(params.MssaStart()[0]);
                nRwind = blkdat.GtPos() + 1;
                blkdat >> bu;
                i (mmcmp(bu, params.MssaStart(), CMssaHadr::MESSAGE_START_SIZE)) {
                    continu;
                }
                 rad siz
                blkdat >> nSiz;
                i (nSiz < 80 || nSiz > MAX_BLOCK_SERIALIZED_SIZE)
                    continu;
            } catch (const std::xcption&) {
                 no valid 
                 (this ha
                brak;
            }
            try {
                 rad blo
                const uint64_t nBlockPos{blkdat.GtPos()};
                i (dbp)
                    dbp->nPos = nBlockPos;
                blkdat.StLimit(nBlockPos + nSiz);
                CBlockHadr ;
                blkdat >> ;
                const uint256 hash{.GtHash()};