Fix for implementation defined behavior causing failures

[mborland]

Closes: #304

[cppalliance-bot]

An automated preview of the documentation is available at https://305.int128.prtest3.cppalliance.org/libs/int128/doc/html/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-01-30 19:33:51 UTC

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.91%. Comparing base (16987b1) to head (83512f7).
⚠️ Report is 4 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #305      +/-   ##
===========================================
- Coverage    98.91%   98.91%   -0.01%     
===========================================
  Files           59       59              
  Lines         5249     5243       -6     
  Branches      1609     1609              
===========================================
- Hits          5192     5186       -6     
  Misses          30       30              
  Partials        27       27              

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