test: Block header validation fixes

[gumb0]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 85.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 94.41%. Comparing base (18b8e95) to head (887d5a0).
Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
test/blockchaintest/blockchaintest_runner.cpp	84.21%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1244      +/-   ##
==========================================
- Coverage   94.55%   94.41%   -0.14%     
==========================================
  Files         175      175              
  Lines       19714    19732      +18     
==========================================
- Hits        18640    18630      -10     
- Misses       1074     1102      +28     

Flag	Coverage Δ
eest_gmp	15.26% <0.00%> (-0.01%)	⬇️
eof_execution_spec_tests	19.90% <80.00%> (+0.04%)	⬆️
ethereum_tests	?
ethereum_tests_silkpre	18.27% <0.00%> (-0.01%)	⬇️
execution_spec_tests	18.78% <85.00%> (+0.23%)	⬆️
unittests	91.75% <5.00%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
test/blockchaintest/blockchaintest_loader.cpp	93.13% <100.00%> (-5.88%)	⬇️
test/state/block.hpp	100.00% <ø> (+33.33%)	⬆️
test/blockchaintest/blockchaintest_runner.cpp	80.26% <84.21%> (-5.39%)	⬇️

... and 9 files with indirect coverage changes

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