Tolerate invalid parents when computing mutation parents

[benjeffery]

Fixes #3303

[codecov]

Codecov Report

❌ Patch coverage is 82.35294% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.80%. Comparing base (1acc108) to head (5e809c0).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
c/tskit/tables.c	82.35%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3309      +/-   ##
==========================================
- Coverage   89.80%   89.80%   -0.01%     
==========================================
  Files          29       29              
  Lines       31026    31043      +17     
  Branches     5679     5682       +3     
==========================================
+ Hits        27863    27877      +14     
- Misses       1777     1779       +2     
- Partials     1386     1387       +1     

Flag	Coverage Δ
c-tests	86.85% <82.35%> (-0.01%)	⬇️
lwt-tests	80.38% <ø> (ø)
python-c-tests	87.05% <ø> (ø)
python-tests	98.84% <ø> (ø)
python-tests-no-jit	33.60% <ø> (ø)
python-tests-numpy1	50.18% <ø> (ø)

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Files with missing lines	Coverage Δ
c/tskit/tables.c	83.08% <82.35%> (-0.01%)	⬇️

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[jeromekelleher]

I like it. Just needs a few more tests.

[jeromekelleher]

Another test checking the parent data is preserved on error

[petrelharp]

if possible we should check the data is preserved on error even if TSK_NO_CHECK_INTEGRITY is on

[benjeffery]

a3e12f7