fixes #1804

[affeldt-aist]

Co-authored-by: @agontard

Motivation for this change

fixes #1804

Checklist

• added corresponding entries in CHANGELOG_UNRELEASED.md

- [ ] added corresponding documentation in the headers

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[t6s]

this change looks contradictory to @CohenCyril 's suggestion in the original discussion

[affeldt-aist]

Yes, the PR was done quickly to check the CI to fuel the discussion. It could be closed now, except that @agontard maybe found an inconsistency in MathComp proper (shouldn't the arguments of ltP be made explicit after all?).