Cannot you find the incomplete repetition with 
/^(.*).*\1$/

[download]
?

If it is complete, you get the whole one.

لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re^3: Finding repeat sequences. (only mostly regex) by choroba
in thread Finding repeat sequences. by BrowserUk

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