CNF.c:insertCompactHash doesn't correctly dirty regions

Consider CNF.c:insertCompactHash:

void
insertCompactHash (Capability *cap,
                   StgCompactNFData *str,
                   StgClosure *p, StgClosure *to)
{
    insertHashTable(str->hash, (StgWord)p, (const void*)to);
    const StgInfoTable *strinfo = &str->header.info;
    if (strinfo == &stg_COMPACT_NFDATA_CLEAN_info) {
        strinfo = &stg_COMPACT_NFDATA_DIRTY_info;
        recordClosureMutated(cap, (StgClosure*)str);
    }
}

At first glance this looks reasonable. However, note how we are dirtying the region:

        strinfo = &stg_COMPACT_NFDATA_DIRTY_info;

This does not do at all what we want; it simply sets the local variable, not the info table pointer.

For this reason compact regions with sharing preservation enabled get added to the mut_list once for every object in the region. Terrible!