Search for exact title with different encoding fails

[MignonBelongie]

If the title of a work has characters with diacritics, searching for it with a string that corresponds to exactly the same title but with a different unicode representation fails.

Evidence / Screenshot (if possible)

This is very hard to demo, because it involves strings which appear identical, and whose encoding can be (and often is) changed by browsers, editors, etc. Therefore, I have created a Colab notebook that demonstrates the error: https://colab.research.google.com/drive/1NiKOD0Md_nR7bPbHXGW4lUnyCbc0sbJ5

Since @cdrini is already aware of the issue, I hope this is sufficient.

Stakeholders

@cdrini

[tfmorris]

To save others having to go and read Python code, the two URLs are:

https://openlibrary.org/search.json?title=Des+filles+bien+élevées (single accented character)
https://openlibrary.org/search.json?title=Des+filles+bien+élevées (non-spacing combining accent)

but even worse

https://openlibrary.org/search.json?title=Des+filles+bien+elevees

returns 0 results.

This is a long standing (over a decade) problem for which there is a well known solution.

Here are some of the related tickets: #11, #149, #178, https://bugs.launchpad.net/openlibrary/+bug/598204

[tfmorris]

On testing.openlibrary.org, all three examples above return the same three works, so this is hopefully close to being resolved by the fix for #7040.

https://testing.openlibrary.org/search.json?title=Des+filles+bien+élevées (single accented character)
https://testing.openlibrary.org/search.json?title=Des+filles+bien+élevées (non-spacing combining accent)
https://testing.openlibrary.org/search.json?title=Des+filles+bien+elevees (no accents)