Fix 2866

[Opt-Mucca]

This fixes the crash from the instance in the comments of #2866

Explanation: While iterating over singletonRows, presolving one of the singletons reduces multiple (probably identical ones) to empty rows. Despite them being reduced singletonRows is not updated (is waiting to be cleared). When the size 0 row is then processed, they are not yet deleted and rowPresolve will be called on them during removeRowSingletons. This will then result in a nested call of removeRowSingletons. This is all fine, until we're back at the original loop, where the counter is at something non-zero, e.g., 2, and the loop is continuing because 2 != 0 (the new size of singletonRows from the nested call.

Fix: I've just changed the != to a <.

@zeddybot I'm assuming you're a bot, and a lot of the information wasn't necessary, but the instance was helpful and the issue was clearly explained.

[codecov]

Codecov Report

❌ Patch coverage is 97.77778% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 73.19%. Comparing base (dfd5cbf) to head (5075f16).
⚠️ Report is 67 commits behind head on latest.

Files with missing lines	Patch %	Lines
highs/util/HighsDynamicLibrary.h	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #3139      +/-   ##
==========================================
+ Coverage   73.15%   73.19%   +0.03%     
==========================================
  Files         430      430              
  Lines      103937   104140     +203     
  Branches    16717    16738      +21     
==========================================
+ Hits        76039    76221     +182     
- Misses      27622    27643      +21     
  Partials      276      276              

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[fwesselm]

@Opt-Mucca, thanks for fixing this!