Formdata ignore epilogue preamble

[KhafraDev]

fixes #4671

Claude generated everything minus the tests

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.84%. Comparing base (fbfac48) to head (ccbbfcc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4672      +/-   ##
==========================================
- Coverage   92.85%   92.84%   -0.01%     
==========================================
  Files         107      107              
  Lines       33505    33499       -6     
==========================================
- Hits        31110    31102       -8     
- Misses       2395     2397       +2     

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[KhafraDev]

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