Copy slice when setting block hash list

[janezpodhostnik]

Solves the block hash list issue seen in #6552

The writing to the bucket was done in a way where the original value of the bucket was also changed. Later when we were checking if there are changes, the original bucket and the new bucket were the same so no changes were written.

This requires an HCU

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 41.23%. Comparing base (edf27b0) to head (6834c07).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6734      +/-   ##
==========================================
- Coverage   41.23%   41.23%   -0.01%     
==========================================
  Files        2054     2054              
  Lines      182364   182367       +3     
==========================================
- Hits        75204    75199       -5     
- Misses     100859   100866       +7     
- Partials     6301     6302       +1     

Flag	Coverage Δ
unittests	41.23% <100.00%> (-0.01%)	⬇️

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[zhangchiqing]

Suggested change

	cpy := make([]byte, len(bucket))
	copy(cpy, bucket)
	if err != nil {
	return err
	}
	if err != nil {
	return err
	}
	cpy := make([]byte, len(bucket))
	copy(cpy, bucket)