Fixes #385: KShape clustering loses first time point

[charavelg]

Copy of #417 with current codebase

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.10%. Comparing base (6bcf978) to head (f76a8c0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #596   +/-   ##
=======================================
  Coverage   90.10%   90.10%           
=======================================
  Files          67       67           
  Lines        6096     6096           
=======================================
  Hits         5493     5493           
  Misses        603      603           

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