add keep_unary for pedigrees and dtwf

[GertjanBisschop]

This pull request stores all nodes through which some ancestral material passes for pedigrees and dtwf simulations when the flag record_unary=True is set. This is a first pass to allow for testing (see #2132).
This pull request requires defining a MSP_NODE_IS_PASS_THROUGH_EVENT (see ). Is this as simple as simply using the next available number in line (#define MSP_NODE_IS_PT_EVENT (1u << 22))?
As with #2130 unit tests are still basic and require further work.

[jeromekelleher]

Nice!

@sgravel I think this should more-or-less do what we want with the pedigree sims, so we could start thinking about trying it out and seeing what we get?

[sgravel]

Perfect! Presumably this does not record the ancestors above the MRCA yet, right?

[GertjanBisschop]

Perfect! Presumably this does not record the ancestors above the MRCA yet, right?

Yes, that's correct @sgravel. This would require an additional flag indicating the stopping point of the simulation. We have been discussing this exact issue though while thinking about potential performance improvements (see #2121).

[sgravel]

Ok, we'll do some testing!

[jeromekelleher]

Let's update this and get it merged I think @GertjanBisschop - I guess we should try to register some issues for any remaining TODOs and corner cases so we don't forget them. We can update to the new API later.

[codecov]

Codecov Report

Merging #2145 (5bf4057) into main (d05b851) will decrease coverage by 0.08%.
The diff coverage is 59.45%.

❗ Current head 5bf4057 differs from pull request most recent head b64100c. Consider uploading reports for the commit b64100c to get more accurate results

@@            Coverage Diff             @@
##             main    #2145      +/-   ##
==========================================
- Coverage   91.45%   91.38%   -0.08%     
==========================================
  Files          20       20              
  Lines       11170    11199      +29     
  Branches     2268     2280      +12     
==========================================
+ Hits        10216    10234      +18     
- Misses        521      529       +8     
- Partials      433      436       +3     

Flag	Coverage Δ
C	91.38% <59.45%> (-0.08%)	⬇️
python	98.74% <ø> (ø)

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Impacted Files	Coverage Δ
lib/msprime.c	85.89% <59.45%> (-0.18%)	⬇️

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[GertjanBisschop]

Not sure how I might have reduced code coverage that significantly. What do I do to fix this?

[GertjanBisschop]

Right I guess this means I'll have to write some additional tests in C.

[jeromekelleher]

Let's have a look through this tomorrow @GertjanBisschop - it might be simpler to push through the final API rather than getting the C test coverage up.

[GertjanBisschop]

Implemented in #2176.