Prevent input=output in tractogram compress

[EmmaRenauld]

Fixes issue #1264

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.44%. Comparing base (df80acf) to head (05221ee).
⚠️ Report is 5 commits behind head on master.

❌ Your patch status has failed because the patch coverage (0.00%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (72.44%) is below the target coverage (75.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1269      +/-   ##
==========================================
- Coverage   72.45%   72.44%   -0.02%     
==========================================
  Files         293      293              
  Lines       25203    25205       +2     
  Branches     3530     3531       +1     
==========================================
- Hits        18262    18260       -2     
  Misses       5450     5450              
- Partials     1491     1495       +4     

Flag	Coverage Δ
smoketests	69.61% <0.00%> (-0.01%)	⬇️
unittests	13.31% <0.00%> (-0.01%)	⬇️

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Components	Coverage Δ
Scripts	75.27% <0.00%> (-0.02%)	⬇️
Library	69.09% <ø> (-0.01%)	⬇️

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